| /* |
| * CFQ, or complete fairness queueing, disk scheduler. |
| * |
| * Based on ideas from a previously unfinished io |
| * scheduler (round robin per-process disk scheduling) and Andrea Arcangeli. |
| * |
| * Copyright (C) 2003 Jens Axboe <axboe@kernel.dk> |
| */ |
| #include <linux/module.h> |
| #include <linux/slab.h> |
| #include <linux/blkdev.h> |
| #include <linux/elevator.h> |
| #include <linux/jiffies.h> |
| #include <linux/rbtree.h> |
| #include <linux/ioprio.h> |
| #include <linux/blktrace_api.h> |
| #include "blk.h" |
| #include "cfq.h" |
| |
| /* |
| * tunables |
| */ |
| /* max queue in one round of service */ |
| static const int cfq_quantum = 8; |
| static const int cfq_fifo_expire[2] = { HZ / 4, HZ / 8 }; |
| /* maximum backwards seek, in KiB */ |
| static const int cfq_back_max = 16 * 1024; |
| /* penalty of a backwards seek */ |
| static const int cfq_back_penalty = 2; |
| static const int cfq_slice_sync = HZ / 10; |
| static int cfq_slice_async = HZ / 25; |
| static const int cfq_slice_async_rq = 2; |
| static int cfq_slice_idle = HZ / 125; |
| static int cfq_group_idle = HZ / 125; |
| static const int cfq_target_latency = HZ * 3/10; /* 300 ms */ |
| static const int cfq_hist_divisor = 4; |
| |
| /* |
| * offset from end of service tree |
| */ |
| #define CFQ_IDLE_DELAY (HZ / 5) |
| |
| /* |
| * below this threshold, we consider thinktime immediate |
| */ |
| #define CFQ_MIN_TT (2) |
| |
| #define CFQ_SLICE_SCALE (5) |
| #define CFQ_HW_QUEUE_MIN (5) |
| #define CFQ_SERVICE_SHIFT 12 |
| |
| #define CFQQ_SEEK_THR (sector_t)(8 * 100) |
| #define CFQQ_CLOSE_THR (sector_t)(8 * 1024) |
| #define CFQQ_SECT_THR_NONROT (sector_t)(2 * 32) |
| #define CFQQ_SEEKY(cfqq) (hweight32(cfqq->seek_history) > 32/8) |
| |
| #define RQ_CIC(rq) icq_to_cic((rq)->elv.icq) |
| #define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elv.priv[0]) |
| #define RQ_CFQG(rq) (struct cfq_group *) ((rq)->elv.priv[1]) |
| |
| static struct kmem_cache *cfq_pool; |
| |
| #define CFQ_PRIO_LISTS IOPRIO_BE_NR |
| #define cfq_class_idle(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_IDLE) |
| #define cfq_class_rt(cfqq) ((cfqq)->ioprio_class == IOPRIO_CLASS_RT) |
| |
| #define sample_valid(samples) ((samples) > 80) |
| #define rb_entry_cfqg(node) rb_entry((node), struct cfq_group, rb_node) |
| |
| struct cfq_ttime { |
| unsigned long last_end_request; |
| |
| unsigned long ttime_total; |
| unsigned long ttime_samples; |
| unsigned long ttime_mean; |
| }; |
| |
| /* |
| * Most of our rbtree usage is for sorting with min extraction, so |
| * if we cache the leftmost node we don't have to walk down the tree |
| * to find it. Idea borrowed from Ingo Molnars CFS scheduler. We should |
| * move this into the elevator for the rq sorting as well. |
| */ |
| struct cfq_rb_root { |
| struct rb_root rb; |
| struct rb_node *left; |
| unsigned count; |
| unsigned total_weight; |
| u64 min_vdisktime; |
| struct cfq_ttime ttime; |
| }; |
| #define CFQ_RB_ROOT (struct cfq_rb_root) { .rb = RB_ROOT, \ |
| .ttime = {.last_end_request = jiffies,},} |
| |
| /* |
| * Per process-grouping structure |
| */ |
| struct cfq_queue { |
| /* reference count */ |
| int ref; |
| /* various state flags, see below */ |
| unsigned int flags; |
| /* parent cfq_data */ |
| struct cfq_data *cfqd; |
| /* service_tree member */ |
| struct rb_node rb_node; |
| /* service_tree key */ |
| unsigned long rb_key; |
| /* prio tree member */ |
| struct rb_node p_node; |
| /* prio tree root we belong to, if any */ |
| struct rb_root *p_root; |
| /* sorted list of pending requests */ |
| struct rb_root sort_list; |
| /* if fifo isn't expired, next request to serve */ |
| struct request *next_rq; |
| /* requests queued in sort_list */ |
| int queued[2]; |
| /* currently allocated requests */ |
| int allocated[2]; |
| /* fifo list of requests in sort_list */ |
| struct list_head fifo; |
| |
| /* time when queue got scheduled in to dispatch first request. */ |
| unsigned long dispatch_start; |
| unsigned int allocated_slice; |
| unsigned int slice_dispatch; |
| /* time when first request from queue completed and slice started. */ |
| unsigned long slice_start; |
| unsigned long slice_end; |
| long slice_resid; |
| |
| /* pending priority requests */ |
| int prio_pending; |
| /* number of requests that are on the dispatch list or inside driver */ |
| int dispatched; |
| |
| /* io prio of this group */ |
| unsigned short ioprio, org_ioprio; |
| unsigned short ioprio_class; |
| |
| pid_t pid; |
| |
| u32 seek_history; |
| sector_t last_request_pos; |
| |
| struct cfq_rb_root *service_tree; |
| struct cfq_queue *new_cfqq; |
| struct cfq_group *cfqg; |
| /* Number of sectors dispatched from queue in single dispatch round */ |
| unsigned long nr_sectors; |
| }; |
| |
| /* |
| * First index in the service_trees. |
| * IDLE is handled separately, so it has negative index |
| */ |
| enum wl_prio_t { |
| BE_WORKLOAD = 0, |
| RT_WORKLOAD = 1, |
| IDLE_WORKLOAD = 2, |
| CFQ_PRIO_NR, |
| }; |
| |
| /* |
| * Second index in the service_trees. |
| */ |
| enum wl_type_t { |
| ASYNC_WORKLOAD = 0, |
| SYNC_NOIDLE_WORKLOAD = 1, |
| SYNC_WORKLOAD = 2 |
| }; |
| |
| /* This is per cgroup per device grouping structure */ |
| struct cfq_group { |
| /* group service_tree member */ |
| struct rb_node rb_node; |
| |
| /* group service_tree key */ |
| u64 vdisktime; |
| unsigned int weight; |
| unsigned int new_weight; |
| bool needs_update; |
| |
| /* number of cfqq currently on this group */ |
| int nr_cfqq; |
| |
| /* |
| * Per group busy queues average. Useful for workload slice calc. We |
| * create the array for each prio class but at run time it is used |
| * only for RT and BE class and slot for IDLE class remains unused. |
| * This is primarily done to avoid confusion and a gcc warning. |
| */ |
| unsigned int busy_queues_avg[CFQ_PRIO_NR]; |
| /* |
| * rr lists of queues with requests. We maintain service trees for |
| * RT and BE classes. These trees are subdivided in subclasses |
| * of SYNC, SYNC_NOIDLE and ASYNC based on workload type. For IDLE |
| * class there is no subclassification and all the cfq queues go on |
| * a single tree service_tree_idle. |
| * Counts are embedded in the cfq_rb_root |
| */ |
| struct cfq_rb_root service_trees[2][3]; |
| struct cfq_rb_root service_tree_idle; |
| |
| unsigned long saved_workload_slice; |
| enum wl_type_t saved_workload; |
| enum wl_prio_t saved_serving_prio; |
| struct blkio_group blkg; |
| #ifdef CONFIG_CFQ_GROUP_IOSCHED |
| struct hlist_node cfqd_node; |
| int ref; |
| #endif |
| /* number of requests that are on the dispatch list or inside driver */ |
| int dispatched; |
| struct cfq_ttime ttime; |
| }; |
| |
| struct cfq_io_cq { |
| struct io_cq icq; /* must be the first member */ |
| struct cfq_queue *cfqq[2]; |
| struct cfq_ttime ttime; |
| }; |
| |
| /* |
| * Per block device queue structure |
| */ |
| struct cfq_data { |
| struct request_queue *queue; |
| /* Root service tree for cfq_groups */ |
| struct cfq_rb_root grp_service_tree; |
| struct cfq_group root_group; |
| |
| /* |
| * The priority currently being served |
| */ |
| enum wl_prio_t serving_prio; |
| enum wl_type_t serving_type; |
| unsigned long workload_expires; |
| struct cfq_group *serving_group; |
| |
| /* |
| * Each priority tree is sorted by next_request position. These |
| * trees are used when determining if two or more queues are |
| * interleaving requests (see cfq_close_cooperator). |
| */ |
| struct rb_root prio_trees[CFQ_PRIO_LISTS]; |
| |
| unsigned int busy_queues; |
| unsigned int busy_sync_queues; |
| |
| int rq_in_driver; |
| int rq_in_flight[2]; |
| |
| /* |
| * queue-depth detection |
| */ |
| int rq_queued; |
| int hw_tag; |
| /* |
| * hw_tag can be |
| * -1 => indeterminate, (cfq will behave as if NCQ is present, to allow better detection) |
| * 1 => NCQ is present (hw_tag_est_depth is the estimated max depth) |
| * 0 => no NCQ |
| */ |
| int hw_tag_est_depth; |
| unsigned int hw_tag_samples; |
| |
| /* |
| * idle window management |
| */ |
| struct timer_list idle_slice_timer; |
| struct work_struct unplug_work; |
| |
| struct cfq_queue *active_queue; |
| struct cfq_io_cq *active_cic; |
| |
| /* |
| * async queue for each priority case |
| */ |
| struct cfq_queue *async_cfqq[2][IOPRIO_BE_NR]; |
| struct cfq_queue *async_idle_cfqq; |
| |
| sector_t last_position; |
| |
| /* |
| * tunables, see top of file |
| */ |
| unsigned int cfq_quantum; |
| unsigned int cfq_fifo_expire[2]; |
| unsigned int cfq_back_penalty; |
| unsigned int cfq_back_max; |
| unsigned int cfq_slice[2]; |
| unsigned int cfq_slice_async_rq; |
| unsigned int cfq_slice_idle; |
| unsigned int cfq_group_idle; |
| unsigned int cfq_latency; |
| |
| /* |
| * Fallback dummy cfqq for extreme OOM conditions |
| */ |
| struct cfq_queue oom_cfqq; |
| |
| unsigned long last_delayed_sync; |
| |
| /* List of cfq groups being managed on this device*/ |
| struct hlist_head cfqg_list; |
| |
| /* Number of groups which are on blkcg->blkg_list */ |
| unsigned int nr_blkcg_linked_grps; |
| }; |
| |
| static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd); |
| |
| static struct cfq_rb_root *service_tree_for(struct cfq_group *cfqg, |
| enum wl_prio_t prio, |
| enum wl_type_t type) |
| { |
| if (!cfqg) |
| return NULL; |
| |
| if (prio == IDLE_WORKLOAD) |
| return &cfqg->service_tree_idle; |
| |
| return &cfqg->service_trees[prio][type]; |
| } |
| |
| enum cfqq_state_flags { |
| CFQ_CFQQ_FLAG_on_rr = 0, /* on round-robin busy list */ |
| CFQ_CFQQ_FLAG_wait_request, /* waiting for a request */ |
| CFQ_CFQQ_FLAG_must_dispatch, /* must be allowed a dispatch */ |
| CFQ_CFQQ_FLAG_must_alloc_slice, /* per-slice must_alloc flag */ |
| CFQ_CFQQ_FLAG_fifo_expire, /* FIFO checked in this slice */ |
| CFQ_CFQQ_FLAG_idle_window, /* slice idling enabled */ |
| CFQ_CFQQ_FLAG_prio_changed, /* task priority has changed */ |
| CFQ_CFQQ_FLAG_slice_new, /* no requests dispatched in slice */ |
| CFQ_CFQQ_FLAG_sync, /* synchronous queue */ |
| CFQ_CFQQ_FLAG_coop, /* cfqq is shared */ |
| CFQ_CFQQ_FLAG_split_coop, /* shared cfqq will be splitted */ |
| CFQ_CFQQ_FLAG_deep, /* sync cfqq experienced large depth */ |
| CFQ_CFQQ_FLAG_wait_busy, /* Waiting for next request */ |
| }; |
| |
| #define CFQ_CFQQ_FNS(name) \ |
| static inline void cfq_mark_cfqq_##name(struct cfq_queue *cfqq) \ |
| { \ |
| (cfqq)->flags |= (1 << CFQ_CFQQ_FLAG_##name); \ |
| } \ |
| static inline void cfq_clear_cfqq_##name(struct cfq_queue *cfqq) \ |
| { \ |
| (cfqq)->flags &= ~(1 << CFQ_CFQQ_FLAG_##name); \ |
| } \ |
| static inline int cfq_cfqq_##name(const struct cfq_queue *cfqq) \ |
| { \ |
| return ((cfqq)->flags & (1 << CFQ_CFQQ_FLAG_##name)) != 0; \ |
| } |
| |
| CFQ_CFQQ_FNS(on_rr); |
| CFQ_CFQQ_FNS(wait_request); |
| CFQ_CFQQ_FNS(must_dispatch); |
| CFQ_CFQQ_FNS(must_alloc_slice); |
| CFQ_CFQQ_FNS(fifo_expire); |
| CFQ_CFQQ_FNS(idle_window); |
| CFQ_CFQQ_FNS(prio_changed); |
| CFQ_CFQQ_FNS(slice_new); |
| CFQ_CFQQ_FNS(sync); |
| CFQ_CFQQ_FNS(coop); |
| CFQ_CFQQ_FNS(split_coop); |
| CFQ_CFQQ_FNS(deep); |
| CFQ_CFQQ_FNS(wait_busy); |
| #undef CFQ_CFQQ_FNS |
| |
| #ifdef CONFIG_CFQ_GROUP_IOSCHED |
| #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
| blk_add_trace_msg((cfqd)->queue, "cfq%d%c %s " fmt, (cfqq)->pid, \ |
| cfq_cfqq_sync((cfqq)) ? 'S' : 'A', \ |
| blkg_path(&(cfqq)->cfqg->blkg), ##args) |
| |
| #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) \ |
| blk_add_trace_msg((cfqd)->queue, "%s " fmt, \ |
| blkg_path(&(cfqg)->blkg), ##args) \ |
| |
| #else |
| #define cfq_log_cfqq(cfqd, cfqq, fmt, args...) \ |
| blk_add_trace_msg((cfqd)->queue, "cfq%d " fmt, (cfqq)->pid, ##args) |
| #define cfq_log_cfqg(cfqd, cfqg, fmt, args...) do {} while (0) |
| #endif |
| #define cfq_log(cfqd, fmt, args...) \ |
| blk_add_trace_msg((cfqd)->queue, "cfq " fmt, ##args) |
| |
| /* Traverses through cfq group service trees */ |
| #define for_each_cfqg_st(cfqg, i, j, st) \ |
| for (i = 0; i <= IDLE_WORKLOAD; i++) \ |
| for (j = 0, st = i < IDLE_WORKLOAD ? &cfqg->service_trees[i][j]\ |
| : &cfqg->service_tree_idle; \ |
| (i < IDLE_WORKLOAD && j <= SYNC_WORKLOAD) || \ |
| (i == IDLE_WORKLOAD && j == 0); \ |
| j++, st = i < IDLE_WORKLOAD ? \ |
| &cfqg->service_trees[i][j]: NULL) \ |
| |
| static inline bool cfq_io_thinktime_big(struct cfq_data *cfqd, |
| struct cfq_ttime *ttime, bool group_idle) |
| { |
| unsigned long slice; |
| if (!sample_valid(ttime->ttime_samples)) |
| return false; |
| if (group_idle) |
| slice = cfqd->cfq_group_idle; |
| else |
| slice = cfqd->cfq_slice_idle; |
| return ttime->ttime_mean > slice; |
| } |
| |
| static inline bool iops_mode(struct cfq_data *cfqd) |
| { |
| /* |
| * If we are not idling on queues and it is a NCQ drive, parallel |
| * execution of requests is on and measuring time is not possible |
| * in most of the cases until and unless we drive shallower queue |
| * depths and that becomes a performance bottleneck. In such cases |
| * switch to start providing fairness in terms of number of IOs. |
| */ |
| if (!cfqd->cfq_slice_idle && cfqd->hw_tag) |
| return true; |
| else |
| return false; |
| } |
| |
| static inline enum wl_prio_t cfqq_prio(struct cfq_queue *cfqq) |
| { |
| if (cfq_class_idle(cfqq)) |
| return IDLE_WORKLOAD; |
| if (cfq_class_rt(cfqq)) |
| return RT_WORKLOAD; |
| return BE_WORKLOAD; |
| } |
| |
| |
| static enum wl_type_t cfqq_type(struct cfq_queue *cfqq) |
| { |
| if (!cfq_cfqq_sync(cfqq)) |
| return ASYNC_WORKLOAD; |
| if (!cfq_cfqq_idle_window(cfqq)) |
| return SYNC_NOIDLE_WORKLOAD; |
| return SYNC_WORKLOAD; |
| } |
| |
| static inline int cfq_group_busy_queues_wl(enum wl_prio_t wl, |
| struct cfq_data *cfqd, |
| struct cfq_group *cfqg) |
| { |
| if (wl == IDLE_WORKLOAD) |
| return cfqg->service_tree_idle.count; |
| |
| return cfqg->service_trees[wl][ASYNC_WORKLOAD].count |
| + cfqg->service_trees[wl][SYNC_NOIDLE_WORKLOAD].count |
| + cfqg->service_trees[wl][SYNC_WORKLOAD].count; |
| } |
| |
| static inline int cfqg_busy_async_queues(struct cfq_data *cfqd, |
| struct cfq_group *cfqg) |
| { |
| return cfqg->service_trees[RT_WORKLOAD][ASYNC_WORKLOAD].count |
| + cfqg->service_trees[BE_WORKLOAD][ASYNC_WORKLOAD].count; |
| } |
| |
| static void cfq_dispatch_insert(struct request_queue *, struct request *); |
| static struct cfq_queue *cfq_get_queue(struct cfq_data *, bool, |
| struct io_context *, gfp_t); |
| |
| static inline struct cfq_io_cq *icq_to_cic(struct io_cq *icq) |
| { |
| /* cic->icq is the first member, %NULL will convert to %NULL */ |
| return container_of(icq, struct cfq_io_cq, icq); |
| } |
| |
| static inline struct cfq_io_cq *cfq_cic_lookup(struct cfq_data *cfqd, |
| struct io_context *ioc) |
| { |
| if (ioc) |
| return icq_to_cic(ioc_lookup_icq(ioc, cfqd->queue)); |
| return NULL; |
| } |
| |
| static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_cq *cic, bool is_sync) |
| { |
| return cic->cfqq[is_sync]; |
| } |
| |
| static inline void cic_set_cfqq(struct cfq_io_cq *cic, struct cfq_queue *cfqq, |
| bool is_sync) |
| { |
| cic->cfqq[is_sync] = cfqq; |
| } |
| |
| static inline struct cfq_data *cic_to_cfqd(struct cfq_io_cq *cic) |
| { |
| return cic->icq.q->elevator->elevator_data; |
| } |
| |
| /* |
| * We regard a request as SYNC, if it's either a read or has the SYNC bit |
| * set (in which case it could also be direct WRITE). |
| */ |
| static inline bool cfq_bio_sync(struct bio *bio) |
| { |
| return bio_data_dir(bio) == READ || (bio->bi_rw & REQ_SYNC); |
| } |
| |
| /* |
| * scheduler run of queue, if there are requests pending and no one in the |
| * driver that will restart queueing |
| */ |
| static inline void cfq_schedule_dispatch(struct cfq_data *cfqd) |
| { |
| if (cfqd->busy_queues) { |
| cfq_log(cfqd, "schedule dispatch"); |
| kblockd_schedule_work(cfqd->queue, &cfqd->unplug_work); |
| } |
| } |
| |
| /* |
| * Scale schedule slice based on io priority. Use the sync time slice only |
| * if a queue is marked sync and has sync io queued. A sync queue with async |
| * io only, should not get full sync slice length. |
| */ |
| static inline int cfq_prio_slice(struct cfq_data *cfqd, bool sync, |
| unsigned short prio) |
| { |
| const int base_slice = cfqd->cfq_slice[sync]; |
| |
| WARN_ON(prio >= IOPRIO_BE_NR); |
| |
| return base_slice + (base_slice/CFQ_SLICE_SCALE * (4 - prio)); |
| } |
| |
| static inline int |
| cfq_prio_to_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| return cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio); |
| } |
| |
| static inline u64 cfq_scale_slice(unsigned long delta, struct cfq_group *cfqg) |
| { |
| u64 d = delta << CFQ_SERVICE_SHIFT; |
| |
| d = d * BLKIO_WEIGHT_DEFAULT; |
| do_div(d, cfqg->weight); |
| return d; |
| } |
| |
| static inline u64 max_vdisktime(u64 min_vdisktime, u64 vdisktime) |
| { |
| s64 delta = (s64)(vdisktime - min_vdisktime); |
| if (delta > 0) |
| min_vdisktime = vdisktime; |
| |
| return min_vdisktime; |
| } |
| |
| static inline u64 min_vdisktime(u64 min_vdisktime, u64 vdisktime) |
| { |
| s64 delta = (s64)(vdisktime - min_vdisktime); |
| if (delta < 0) |
| min_vdisktime = vdisktime; |
| |
| return min_vdisktime; |
| } |
| |
| static void update_min_vdisktime(struct cfq_rb_root *st) |
| { |
| struct cfq_group *cfqg; |
| |
| if (st->left) { |
| cfqg = rb_entry_cfqg(st->left); |
| st->min_vdisktime = max_vdisktime(st->min_vdisktime, |
| cfqg->vdisktime); |
| } |
| } |
| |
| /* |
| * get averaged number of queues of RT/BE priority. |
| * average is updated, with a formula that gives more weight to higher numbers, |
| * to quickly follows sudden increases and decrease slowly |
| */ |
| |
| static inline unsigned cfq_group_get_avg_queues(struct cfq_data *cfqd, |
| struct cfq_group *cfqg, bool rt) |
| { |
| unsigned min_q, max_q; |
| unsigned mult = cfq_hist_divisor - 1; |
| unsigned round = cfq_hist_divisor / 2; |
| unsigned busy = cfq_group_busy_queues_wl(rt, cfqd, cfqg); |
| |
| min_q = min(cfqg->busy_queues_avg[rt], busy); |
| max_q = max(cfqg->busy_queues_avg[rt], busy); |
| cfqg->busy_queues_avg[rt] = (mult * max_q + min_q + round) / |
| cfq_hist_divisor; |
| return cfqg->busy_queues_avg[rt]; |
| } |
| |
| static inline unsigned |
| cfq_group_slice(struct cfq_data *cfqd, struct cfq_group *cfqg) |
| { |
| struct cfq_rb_root *st = &cfqd->grp_service_tree; |
| |
| return cfq_target_latency * cfqg->weight / st->total_weight; |
| } |
| |
| static inline unsigned |
| cfq_scaled_cfqq_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| unsigned slice = cfq_prio_to_slice(cfqd, cfqq); |
| if (cfqd->cfq_latency) { |
| /* |
| * interested queues (we consider only the ones with the same |
| * priority class in the cfq group) |
| */ |
| unsigned iq = cfq_group_get_avg_queues(cfqd, cfqq->cfqg, |
| cfq_class_rt(cfqq)); |
| unsigned sync_slice = cfqd->cfq_slice[1]; |
| unsigned expect_latency = sync_slice * iq; |
| unsigned group_slice = cfq_group_slice(cfqd, cfqq->cfqg); |
| |
| if (expect_latency > group_slice) { |
| unsigned base_low_slice = 2 * cfqd->cfq_slice_idle; |
| /* scale low_slice according to IO priority |
| * and sync vs async */ |
| unsigned low_slice = |
| min(slice, base_low_slice * slice / sync_slice); |
| /* the adapted slice value is scaled to fit all iqs |
| * into the target latency */ |
| slice = max(slice * group_slice / expect_latency, |
| low_slice); |
| } |
| } |
| return slice; |
| } |
| |
| static inline void |
| cfq_set_prio_slice(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| unsigned slice = cfq_scaled_cfqq_slice(cfqd, cfqq); |
| |
| cfqq->slice_start = jiffies; |
| cfqq->slice_end = jiffies + slice; |
| cfqq->allocated_slice = slice; |
| cfq_log_cfqq(cfqd, cfqq, "set_slice=%lu", cfqq->slice_end - jiffies); |
| } |
| |
| /* |
| * We need to wrap this check in cfq_cfqq_slice_new(), since ->slice_end |
| * isn't valid until the first request from the dispatch is activated |
| * and the slice time set. |
| */ |
| static inline bool cfq_slice_used(struct cfq_queue *cfqq) |
| { |
| if (cfq_cfqq_slice_new(cfqq)) |
| return false; |
| if (time_before(jiffies, cfqq->slice_end)) |
| return false; |
| |
| return true; |
| } |
| |
| /* |
| * Lifted from AS - choose which of rq1 and rq2 that is best served now. |
| * We choose the request that is closest to the head right now. Distance |
| * behind the head is penalized and only allowed to a certain extent. |
| */ |
| static struct request * |
| cfq_choose_req(struct cfq_data *cfqd, struct request *rq1, struct request *rq2, sector_t last) |
| { |
| sector_t s1, s2, d1 = 0, d2 = 0; |
| unsigned long back_max; |
| #define CFQ_RQ1_WRAP 0x01 /* request 1 wraps */ |
| #define CFQ_RQ2_WRAP 0x02 /* request 2 wraps */ |
| unsigned wrap = 0; /* bit mask: requests behind the disk head? */ |
| |
| if (rq1 == NULL || rq1 == rq2) |
| return rq2; |
| if (rq2 == NULL) |
| return rq1; |
| |
| if (rq_is_sync(rq1) != rq_is_sync(rq2)) |
| return rq_is_sync(rq1) ? rq1 : rq2; |
| |
| if ((rq1->cmd_flags ^ rq2->cmd_flags) & REQ_PRIO) |
| return rq1->cmd_flags & REQ_PRIO ? rq1 : rq2; |
| |
| s1 = blk_rq_pos(rq1); |
| s2 = blk_rq_pos(rq2); |
| |
| /* |
| * by definition, 1KiB is 2 sectors |
| */ |
| back_max = cfqd->cfq_back_max * 2; |
| |
| /* |
| * Strict one way elevator _except_ in the case where we allow |
| * short backward seeks which are biased as twice the cost of a |
| * similar forward seek. |
| */ |
| if (s1 >= last) |
| d1 = s1 - last; |
| else if (s1 + back_max >= last) |
| d1 = (last - s1) * cfqd->cfq_back_penalty; |
| else |
| wrap |= CFQ_RQ1_WRAP; |
| |
| if (s2 >= last) |
| d2 = s2 - last; |
| else if (s2 + back_max >= last) |
| d2 = (last - s2) * cfqd->cfq_back_penalty; |
| else |
| wrap |= CFQ_RQ2_WRAP; |
| |
| /* Found required data */ |
| |
| /* |
| * By doing switch() on the bit mask "wrap" we avoid having to |
| * check two variables for all permutations: --> faster! |
| */ |
| switch (wrap) { |
| case 0: /* common case for CFQ: rq1 and rq2 not wrapped */ |
| if (d1 < d2) |
| return rq1; |
| else if (d2 < d1) |
| return rq2; |
| else { |
| if (s1 >= s2) |
| return rq1; |
| else |
| return rq2; |
| } |
| |
| case CFQ_RQ2_WRAP: |
| return rq1; |
| case CFQ_RQ1_WRAP: |
| return rq2; |
| case (CFQ_RQ1_WRAP|CFQ_RQ2_WRAP): /* both rqs wrapped */ |
| default: |
| /* |
| * Since both rqs are wrapped, |
| * start with the one that's further behind head |
| * (--> only *one* back seek required), |
| * since back seek takes more time than forward. |
| */ |
| if (s1 <= s2) |
| return rq1; |
| else |
| return rq2; |
| } |
| } |
| |
| /* |
| * The below is leftmost cache rbtree addon |
| */ |
| static struct cfq_queue *cfq_rb_first(struct cfq_rb_root *root) |
| { |
| /* Service tree is empty */ |
| if (!root->count) |
| return NULL; |
| |
| if (!root->left) |
| root->left = rb_first(&root->rb); |
| |
| if (root->left) |
| return rb_entry(root->left, struct cfq_queue, rb_node); |
| |
| return NULL; |
| } |
| |
| static struct cfq_group *cfq_rb_first_group(struct cfq_rb_root *root) |
| { |
| if (!root->left) |
| root->left = rb_first(&root->rb); |
| |
| if (root->left) |
| return rb_entry_cfqg(root->left); |
| |
| return NULL; |
| } |
| |
| static void rb_erase_init(struct rb_node *n, struct rb_root *root) |
| { |
| rb_erase(n, root); |
| RB_CLEAR_NODE(n); |
| } |
| |
| static void cfq_rb_erase(struct rb_node *n, struct cfq_rb_root *root) |
| { |
| if (root->left == n) |
| root->left = NULL; |
| rb_erase_init(n, &root->rb); |
| --root->count; |
| } |
| |
| /* |
| * would be nice to take fifo expire time into account as well |
| */ |
| static struct request * |
| cfq_find_next_rq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct request *last) |
| { |
| struct rb_node *rbnext = rb_next(&last->rb_node); |
| struct rb_node *rbprev = rb_prev(&last->rb_node); |
| struct request *next = NULL, *prev = NULL; |
| |
| BUG_ON(RB_EMPTY_NODE(&last->rb_node)); |
| |
| if (rbprev) |
| prev = rb_entry_rq(rbprev); |
| |
| if (rbnext) |
| next = rb_entry_rq(rbnext); |
| else { |
| rbnext = rb_first(&cfqq->sort_list); |
| if (rbnext && rbnext != &last->rb_node) |
| next = rb_entry_rq(rbnext); |
| } |
| |
| return cfq_choose_req(cfqd, next, prev, blk_rq_pos(last)); |
| } |
| |
| static unsigned long cfq_slice_offset(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| /* |
| * just an approximation, should be ok. |
| */ |
| return (cfqq->cfqg->nr_cfqq - 1) * (cfq_prio_slice(cfqd, 1, 0) - |
| cfq_prio_slice(cfqd, cfq_cfqq_sync(cfqq), cfqq->ioprio)); |
| } |
| |
| static inline s64 |
| cfqg_key(struct cfq_rb_root *st, struct cfq_group *cfqg) |
| { |
| return cfqg->vdisktime - st->min_vdisktime; |
| } |
| |
| static void |
| __cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) |
| { |
| struct rb_node **node = &st->rb.rb_node; |
| struct rb_node *parent = NULL; |
| struct cfq_group *__cfqg; |
| s64 key = cfqg_key(st, cfqg); |
| int left = 1; |
| |
| while (*node != NULL) { |
| parent = *node; |
| __cfqg = rb_entry_cfqg(parent); |
| |
| if (key < cfqg_key(st, __cfqg)) |
| node = &parent->rb_left; |
| else { |
| node = &parent->rb_right; |
| left = 0; |
| } |
| } |
| |
| if (left) |
| st->left = &cfqg->rb_node; |
| |
| rb_link_node(&cfqg->rb_node, parent, node); |
| rb_insert_color(&cfqg->rb_node, &st->rb); |
| } |
| |
| static void |
| cfq_update_group_weight(struct cfq_group *cfqg) |
| { |
| BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); |
| if (cfqg->needs_update) { |
| cfqg->weight = cfqg->new_weight; |
| cfqg->needs_update = false; |
| } |
| } |
| |
| static void |
| cfq_group_service_tree_add(struct cfq_rb_root *st, struct cfq_group *cfqg) |
| { |
| BUG_ON(!RB_EMPTY_NODE(&cfqg->rb_node)); |
| |
| cfq_update_group_weight(cfqg); |
| __cfq_group_service_tree_add(st, cfqg); |
| st->total_weight += cfqg->weight; |
| } |
| |
| static void |
| cfq_group_notify_queue_add(struct cfq_data *cfqd, struct cfq_group *cfqg) |
| { |
| struct cfq_rb_root *st = &cfqd->grp_service_tree; |
| struct cfq_group *__cfqg; |
| struct rb_node *n; |
| |
| cfqg->nr_cfqq++; |
| if (!RB_EMPTY_NODE(&cfqg->rb_node)) |
| return; |
| |
| /* |
| * Currently put the group at the end. Later implement something |
| * so that groups get lesser vtime based on their weights, so that |
| * if group does not loose all if it was not continuously backlogged. |
| */ |
| n = rb_last(&st->rb); |
| if (n) { |
| __cfqg = rb_entry_cfqg(n); |
| cfqg->vdisktime = __cfqg->vdisktime + CFQ_IDLE_DELAY; |
| } else |
| cfqg->vdisktime = st->min_vdisktime; |
| cfq_group_service_tree_add(st, cfqg); |
| } |
| |
| static void |
| cfq_group_service_tree_del(struct cfq_rb_root *st, struct cfq_group *cfqg) |
| { |
| st->total_weight -= cfqg->weight; |
| if (!RB_EMPTY_NODE(&cfqg->rb_node)) |
| cfq_rb_erase(&cfqg->rb_node, st); |
| } |
| |
| static void |
| cfq_group_notify_queue_del(struct cfq_data *cfqd, struct cfq_group *cfqg) |
| { |
| struct cfq_rb_root *st = &cfqd->grp_service_tree; |
| |
| BUG_ON(cfqg->nr_cfqq < 1); |
| cfqg->nr_cfqq--; |
| |
| /* If there are other cfq queues under this group, don't delete it */ |
| if (cfqg->nr_cfqq) |
| return; |
| |
| cfq_log_cfqg(cfqd, cfqg, "del_from_rr group"); |
| cfq_group_service_tree_del(st, cfqg); |
| cfqg->saved_workload_slice = 0; |
| cfq_blkiocg_update_dequeue_stats(&cfqg->blkg, 1); |
| } |
| |
| static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq, |
| unsigned int *unaccounted_time) |
| { |
| unsigned int slice_used; |
| |
| /* |
| * Queue got expired before even a single request completed or |
| * got expired immediately after first request completion. |
| */ |
| if (!cfqq->slice_start || cfqq->slice_start == jiffies) { |
| /* |
| * Also charge the seek time incurred to the group, otherwise |
| * if there are mutiple queues in the group, each can dispatch |
| * a single request on seeky media and cause lots of seek time |
| * and group will never know it. |
| */ |
| slice_used = max_t(unsigned, (jiffies - cfqq->dispatch_start), |
| 1); |
| } else { |
| slice_used = jiffies - cfqq->slice_start; |
| if (slice_used > cfqq->allocated_slice) { |
| *unaccounted_time = slice_used - cfqq->allocated_slice; |
| slice_used = cfqq->allocated_slice; |
| } |
| if (time_after(cfqq->slice_start, cfqq->dispatch_start)) |
| *unaccounted_time += cfqq->slice_start - |
| cfqq->dispatch_start; |
| } |
| |
| return slice_used; |
| } |
| |
| static void cfq_group_served(struct cfq_data *cfqd, struct cfq_group *cfqg, |
| struct cfq_queue *cfqq) |
| { |
| struct cfq_rb_root *st = &cfqd->grp_service_tree; |
| unsigned int used_sl, charge, unaccounted_sl = 0; |
| int nr_sync = cfqg->nr_cfqq - cfqg_busy_async_queues(cfqd, cfqg) |
| - cfqg->service_tree_idle.count; |
| |
| BUG_ON(nr_sync < 0); |
| used_sl = charge = cfq_cfqq_slice_usage(cfqq, &unaccounted_sl); |
| |
| if (iops_mode(cfqd)) |
| charge = cfqq->slice_dispatch; |
| else if (!cfq_cfqq_sync(cfqq) && !nr_sync) |
| charge = cfqq->allocated_slice; |
| |
| /* Can't update vdisktime while group is on service tree */ |
| cfq_group_service_tree_del(st, cfqg); |
| cfqg->vdisktime += cfq_scale_slice(charge, cfqg); |
| /* If a new weight was requested, update now, off tree */ |
| cfq_group_service_tree_add(st, cfqg); |
| |
| /* This group is being expired. Save the context */ |
| if (time_after(cfqd->workload_expires, jiffies)) { |
| cfqg->saved_workload_slice = cfqd->workload_expires |
| - jiffies; |
| cfqg->saved_workload = cfqd->serving_type; |
| cfqg->saved_serving_prio = cfqd->serving_prio; |
| } else |
| cfqg->saved_workload_slice = 0; |
| |
| cfq_log_cfqg(cfqd, cfqg, "served: vt=%llu min_vt=%llu", cfqg->vdisktime, |
| st->min_vdisktime); |
| cfq_log_cfqq(cfqq->cfqd, cfqq, |
| "sl_used=%u disp=%u charge=%u iops=%u sect=%lu", |
| used_sl, cfqq->slice_dispatch, charge, |
| iops_mode(cfqd), cfqq->nr_sectors); |
| cfq_blkiocg_update_timeslice_used(&cfqg->blkg, used_sl, |
| unaccounted_sl); |
| cfq_blkiocg_set_start_empty_time(&cfqg->blkg); |
| } |
| |
| #ifdef CONFIG_CFQ_GROUP_IOSCHED |
| static inline struct cfq_group *cfqg_of_blkg(struct blkio_group *blkg) |
| { |
| if (blkg) |
| return container_of(blkg, struct cfq_group, blkg); |
| return NULL; |
| } |
| |
| static void cfq_update_blkio_group_weight(void *key, struct blkio_group *blkg, |
| unsigned int weight) |
| { |
| struct cfq_group *cfqg = cfqg_of_blkg(blkg); |
| cfqg->new_weight = weight; |
| cfqg->needs_update = true; |
| } |
| |
| static void cfq_init_add_cfqg_lists(struct cfq_data *cfqd, |
| struct cfq_group *cfqg, struct blkio_cgroup *blkcg) |
| { |
| struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; |
| unsigned int major, minor; |
| |
| /* |
| * Add group onto cgroup list. It might happen that bdi->dev is |
| * not initialized yet. Initialize this new group without major |
| * and minor info and this info will be filled in once a new thread |
| * comes for IO. |
| */ |
| if (bdi->dev) { |
| sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); |
| cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, |
| (void *)cfqd, MKDEV(major, minor)); |
| } else |
| cfq_blkiocg_add_blkio_group(blkcg, &cfqg->blkg, |
| (void *)cfqd, 0); |
| |
| cfqd->nr_blkcg_linked_grps++; |
| cfqg->weight = blkcg_get_weight(blkcg, cfqg->blkg.dev); |
| |
| /* Add group on cfqd list */ |
| hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list); |
| } |
| |
| /* |
| * Should be called from sleepable context. No request queue lock as per |
| * cpu stats are allocated dynamically and alloc_percpu needs to be called |
| * from sleepable context. |
| */ |
| static struct cfq_group * cfq_alloc_cfqg(struct cfq_data *cfqd) |
| { |
| struct cfq_group *cfqg = NULL; |
| int i, j, ret; |
| struct cfq_rb_root *st; |
| |
| cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node); |
| if (!cfqg) |
| return NULL; |
| |
| for_each_cfqg_st(cfqg, i, j, st) |
| *st = CFQ_RB_ROOT; |
| RB_CLEAR_NODE(&cfqg->rb_node); |
| |
| cfqg->ttime.last_end_request = jiffies; |
| |
| /* |
| * Take the initial reference that will be released on destroy |
| * This can be thought of a joint reference by cgroup and |
| * elevator which will be dropped by either elevator exit |
| * or cgroup deletion path depending on who is exiting first. |
| */ |
| cfqg->ref = 1; |
| |
| ret = blkio_alloc_blkg_stats(&cfqg->blkg); |
| if (ret) { |
| kfree(cfqg); |
| return NULL; |
| } |
| |
| return cfqg; |
| } |
| |
| static struct cfq_group * |
| cfq_find_cfqg(struct cfq_data *cfqd, struct blkio_cgroup *blkcg) |
| { |
| struct cfq_group *cfqg = NULL; |
| void *key = cfqd; |
| struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; |
| unsigned int major, minor; |
| |
| /* |
| * This is the common case when there are no blkio cgroups. |
| * Avoid lookup in this case |
| */ |
| if (blkcg == &blkio_root_cgroup) |
| cfqg = &cfqd->root_group; |
| else |
| cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); |
| |
| if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { |
| sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); |
| cfqg->blkg.dev = MKDEV(major, minor); |
| } |
| |
| return cfqg; |
| } |
| |
| /* |
| * Search for the cfq group current task belongs to. request_queue lock must |
| * be held. |
| */ |
| static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) |
| { |
| struct blkio_cgroup *blkcg; |
| struct cfq_group *cfqg = NULL, *__cfqg = NULL; |
| struct request_queue *q = cfqd->queue; |
| |
| rcu_read_lock(); |
| blkcg = task_blkio_cgroup(current); |
| cfqg = cfq_find_cfqg(cfqd, blkcg); |
| if (cfqg) { |
| rcu_read_unlock(); |
| return cfqg; |
| } |
| |
| /* |
| * Need to allocate a group. Allocation of group also needs allocation |
| * of per cpu stats which in-turn takes a mutex() and can block. Hence |
| * we need to drop rcu lock and queue_lock before we call alloc. |
| * |
| * Not taking any queue reference here and assuming that queue is |
| * around by the time we return. CFQ queue allocation code does |
| * the same. It might be racy though. |
| */ |
| |
| rcu_read_unlock(); |
| spin_unlock_irq(q->queue_lock); |
| |
| cfqg = cfq_alloc_cfqg(cfqd); |
| |
| spin_lock_irq(q->queue_lock); |
| |
| rcu_read_lock(); |
| blkcg = task_blkio_cgroup(current); |
| |
| /* |
| * If some other thread already allocated the group while we were |
| * not holding queue lock, free up the group |
| */ |
| __cfqg = cfq_find_cfqg(cfqd, blkcg); |
| |
| if (__cfqg) { |
| kfree(cfqg); |
| rcu_read_unlock(); |
| return __cfqg; |
| } |
| |
| if (!cfqg) |
| cfqg = &cfqd->root_group; |
| |
| cfq_init_add_cfqg_lists(cfqd, cfqg, blkcg); |
| rcu_read_unlock(); |
| return cfqg; |
| } |
| |
| static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) |
| { |
| cfqg->ref++; |
| return cfqg; |
| } |
| |
| static void cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) |
| { |
| /* Currently, all async queues are mapped to root group */ |
| if (!cfq_cfqq_sync(cfqq)) |
| cfqg = &cfqq->cfqd->root_group; |
| |
| cfqq->cfqg = cfqg; |
| /* cfqq reference on cfqg */ |
| cfqq->cfqg->ref++; |
| } |
| |
| static void cfq_put_cfqg(struct cfq_group *cfqg) |
| { |
| struct cfq_rb_root *st; |
| int i, j; |
| |
| BUG_ON(cfqg->ref <= 0); |
| cfqg->ref--; |
| if (cfqg->ref) |
| return; |
| for_each_cfqg_st(cfqg, i, j, st) |
| BUG_ON(!RB_EMPTY_ROOT(&st->rb)); |
| free_percpu(cfqg->blkg.stats_cpu); |
| kfree(cfqg); |
| } |
| |
| static void cfq_destroy_cfqg(struct cfq_data *cfqd, struct cfq_group *cfqg) |
| { |
| /* Something wrong if we are trying to remove same group twice */ |
| BUG_ON(hlist_unhashed(&cfqg->cfqd_node)); |
| |
| hlist_del_init(&cfqg->cfqd_node); |
| |
| BUG_ON(cfqd->nr_blkcg_linked_grps <= 0); |
| cfqd->nr_blkcg_linked_grps--; |
| |
| /* |
| * Put the reference taken at the time of creation so that when all |
| * queues are gone, group can be destroyed. |
| */ |
| cfq_put_cfqg(cfqg); |
| } |
| |
| static void cfq_release_cfq_groups(struct cfq_data *cfqd) |
| { |
| struct hlist_node *pos, *n; |
| struct cfq_group *cfqg; |
| |
| hlist_for_each_entry_safe(cfqg, pos, n, &cfqd->cfqg_list, cfqd_node) { |
| /* |
| * If cgroup removal path got to blk_group first and removed |
| * it from cgroup list, then it will take care of destroying |
| * cfqg also. |
| */ |
| if (!cfq_blkiocg_del_blkio_group(&cfqg->blkg)) |
| cfq_destroy_cfqg(cfqd, cfqg); |
| } |
| } |
| |
| /* |
| * Blk cgroup controller notification saying that blkio_group object is being |
| * delinked as associated cgroup object is going away. That also means that |
| * no new IO will come in this group. So get rid of this group as soon as |
| * any pending IO in the group is finished. |
| * |
| * This function is called under rcu_read_lock(). key is the rcu protected |
| * pointer. That means "key" is a valid cfq_data pointer as long as we are rcu |
| * read lock. |
| * |
| * "key" was fetched from blkio_group under blkio_cgroup->lock. That means |
| * it should not be NULL as even if elevator was exiting, cgroup deltion |
| * path got to it first. |
| */ |
| static void cfq_unlink_blkio_group(void *key, struct blkio_group *blkg) |
| { |
| unsigned long flags; |
| struct cfq_data *cfqd = key; |
| |
| spin_lock_irqsave(cfqd->queue->queue_lock, flags); |
| cfq_destroy_cfqg(cfqd, cfqg_of_blkg(blkg)); |
| spin_unlock_irqrestore(cfqd->queue->queue_lock, flags); |
| } |
| |
| #else /* GROUP_IOSCHED */ |
| static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd) |
| { |
| return &cfqd->root_group; |
| } |
| |
| static inline struct cfq_group *cfq_ref_get_cfqg(struct cfq_group *cfqg) |
| { |
| return cfqg; |
| } |
| |
| static inline void |
| cfq_link_cfqq_cfqg(struct cfq_queue *cfqq, struct cfq_group *cfqg) { |
| cfqq->cfqg = cfqg; |
| } |
| |
| static void cfq_release_cfq_groups(struct cfq_data *cfqd) {} |
| static inline void cfq_put_cfqg(struct cfq_group *cfqg) {} |
| |
| #endif /* GROUP_IOSCHED */ |
| |
| /* |
| * The cfqd->service_trees holds all pending cfq_queue's that have |
| * requests waiting to be processed. It is sorted in the order that |
| * we will service the queues. |
| */ |
| static void cfq_service_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| bool add_front) |
| { |
| struct rb_node **p, *parent; |
| struct cfq_queue *__cfqq; |
| unsigned long rb_key; |
| struct cfq_rb_root *service_tree; |
| int left; |
| int new_cfqq = 1; |
| |
| service_tree = service_tree_for(cfqq->cfqg, cfqq_prio(cfqq), |
| cfqq_type(cfqq)); |
| if (cfq_class_idle(cfqq)) { |
| rb_key = CFQ_IDLE_DELAY; |
| parent = rb_last(&service_tree->rb); |
| if (parent && parent != &cfqq->rb_node) { |
| __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
| rb_key += __cfqq->rb_key; |
| } else |
| rb_key += jiffies; |
| } else if (!add_front) { |
| /* |
| * Get our rb key offset. Subtract any residual slice |
| * value carried from last service. A negative resid |
| * count indicates slice overrun, and this should position |
| * the next service time further away in the tree. |
| */ |
| rb_key = cfq_slice_offset(cfqd, cfqq) + jiffies; |
| rb_key -= cfqq->slice_resid; |
| cfqq->slice_resid = 0; |
| } else { |
| rb_key = -HZ; |
| __cfqq = cfq_rb_first(service_tree); |
| rb_key += __cfqq ? __cfqq->rb_key : jiffies; |
| } |
| |
| if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
| new_cfqq = 0; |
| /* |
| * same position, nothing more to do |
| */ |
| if (rb_key == cfqq->rb_key && |
| cfqq->service_tree == service_tree) |
| return; |
| |
| cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
| cfqq->service_tree = NULL; |
| } |
| |
| left = 1; |
| parent = NULL; |
| cfqq->service_tree = service_tree; |
| p = &service_tree->rb.rb_node; |
| while (*p) { |
| struct rb_node **n; |
| |
| parent = *p; |
| __cfqq = rb_entry(parent, struct cfq_queue, rb_node); |
| |
| /* |
| * sort by key, that represents service time. |
| */ |
| if (time_before(rb_key, __cfqq->rb_key)) |
| n = &(*p)->rb_left; |
| else { |
| n = &(*p)->rb_right; |
| left = 0; |
| } |
| |
| p = n; |
| } |
| |
| if (left) |
| service_tree->left = &cfqq->rb_node; |
| |
| cfqq->rb_key = rb_key; |
| rb_link_node(&cfqq->rb_node, parent, p); |
| rb_insert_color(&cfqq->rb_node, &service_tree->rb); |
| service_tree->count++; |
| if (add_front || !new_cfqq) |
| return; |
| cfq_group_notify_queue_add(cfqd, cfqq->cfqg); |
| } |
| |
| static struct cfq_queue * |
| cfq_prio_tree_lookup(struct cfq_data *cfqd, struct rb_root *root, |
| sector_t sector, struct rb_node **ret_parent, |
| struct rb_node ***rb_link) |
| { |
| struct rb_node **p, *parent; |
| struct cfq_queue *cfqq = NULL; |
| |
| parent = NULL; |
| p = &root->rb_node; |
| while (*p) { |
| struct rb_node **n; |
| |
| parent = *p; |
| cfqq = rb_entry(parent, struct cfq_queue, p_node); |
| |
| /* |
| * Sort strictly based on sector. Smallest to the left, |
| * largest to the right. |
| */ |
| if (sector > blk_rq_pos(cfqq->next_rq)) |
| n = &(*p)->rb_right; |
| else if (sector < blk_rq_pos(cfqq->next_rq)) |
| n = &(*p)->rb_left; |
| else |
| break; |
| p = n; |
| cfqq = NULL; |
| } |
| |
| *ret_parent = parent; |
| if (rb_link) |
| *rb_link = p; |
| return cfqq; |
| } |
| |
| static void cfq_prio_tree_add(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| struct rb_node **p, *parent; |
| struct cfq_queue *__cfqq; |
| |
| if (cfqq->p_root) { |
| rb_erase(&cfqq->p_node, cfqq->p_root); |
| cfqq->p_root = NULL; |
| } |
| |
| if (cfq_class_idle(cfqq)) |
| return; |
| if (!cfqq->next_rq) |
| return; |
| |
| cfqq->p_root = &cfqd->prio_trees[cfqq->org_ioprio]; |
| __cfqq = cfq_prio_tree_lookup(cfqd, cfqq->p_root, |
| blk_rq_pos(cfqq->next_rq), &parent, &p); |
| if (!__cfqq) { |
| rb_link_node(&cfqq->p_node, parent, p); |
| rb_insert_color(&cfqq->p_node, cfqq->p_root); |
| } else |
| cfqq->p_root = NULL; |
| } |
| |
| /* |
| * Update cfqq's position in the service tree. |
| */ |
| static void cfq_resort_rr_list(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| /* |
| * Resorting requires the cfqq to be on the RR list already. |
| */ |
| if (cfq_cfqq_on_rr(cfqq)) { |
| cfq_service_tree_add(cfqd, cfqq, 0); |
| cfq_prio_tree_add(cfqd, cfqq); |
| } |
| } |
| |
| /* |
| * add to busy list of queues for service, trying to be fair in ordering |
| * the pending list according to last request service |
| */ |
| static void cfq_add_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "add_to_rr"); |
| BUG_ON(cfq_cfqq_on_rr(cfqq)); |
| cfq_mark_cfqq_on_rr(cfqq); |
| cfqd->busy_queues++; |
| if (cfq_cfqq_sync(cfqq)) |
| cfqd->busy_sync_queues++; |
| |
| cfq_resort_rr_list(cfqd, cfqq); |
| } |
| |
| /* |
| * Called when the cfqq no longer has requests pending, remove it from |
| * the service tree. |
| */ |
| static void cfq_del_cfqq_rr(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "del_from_rr"); |
| BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
| cfq_clear_cfqq_on_rr(cfqq); |
| |
| if (!RB_EMPTY_NODE(&cfqq->rb_node)) { |
| cfq_rb_erase(&cfqq->rb_node, cfqq->service_tree); |
| cfqq->service_tree = NULL; |
| } |
| if (cfqq->p_root) { |
| rb_erase(&cfqq->p_node, cfqq->p_root); |
| cfqq->p_root = NULL; |
| } |
| |
| cfq_group_notify_queue_del(cfqd, cfqq->cfqg); |
| BUG_ON(!cfqd->busy_queues); |
| cfqd->busy_queues--; |
| if (cfq_cfqq_sync(cfqq)) |
| cfqd->busy_sync_queues--; |
| } |
| |
| /* |
| * rb tree support functions |
| */ |
| static void cfq_del_rq_rb(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| const int sync = rq_is_sync(rq); |
| |
| BUG_ON(!cfqq->queued[sync]); |
| cfqq->queued[sync]--; |
| |
| elv_rb_del(&cfqq->sort_list, rq); |
| |
| if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) { |
| /* |
| * Queue will be deleted from service tree when we actually |
| * expire it later. Right now just remove it from prio tree |
| * as it is empty. |
| */ |
| if (cfqq->p_root) { |
| rb_erase(&cfqq->p_node, cfqq->p_root); |
| cfqq->p_root = NULL; |
| } |
| } |
| } |
| |
| static void cfq_add_rq_rb(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| struct cfq_data *cfqd = cfqq->cfqd; |
| struct request *prev; |
| |
| cfqq->queued[rq_is_sync(rq)]++; |
| |
| elv_rb_add(&cfqq->sort_list, rq); |
| |
| if (!cfq_cfqq_on_rr(cfqq)) |
| cfq_add_cfqq_rr(cfqd, cfqq); |
| |
| /* |
| * check if this request is a better next-serve candidate |
| */ |
| prev = cfqq->next_rq; |
| cfqq->next_rq = cfq_choose_req(cfqd, cfqq->next_rq, rq, cfqd->last_position); |
| |
| /* |
| * adjust priority tree position, if ->next_rq changes |
| */ |
| if (prev != cfqq->next_rq) |
| cfq_prio_tree_add(cfqd, cfqq); |
| |
| BUG_ON(!cfqq->next_rq); |
| } |
| |
| static void cfq_reposition_rq_rb(struct cfq_queue *cfqq, struct request *rq) |
| { |
| elv_rb_del(&cfqq->sort_list, rq); |
| cfqq->queued[rq_is_sync(rq)]--; |
| cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, |
| rq_data_dir(rq), rq_is_sync(rq)); |
| cfq_add_rq_rb(rq); |
| cfq_blkiocg_update_io_add_stats(&(RQ_CFQG(rq))->blkg, |
| &cfqq->cfqd->serving_group->blkg, rq_data_dir(rq), |
| rq_is_sync(rq)); |
| } |
| |
| static struct request * |
| cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio) |
| { |
| struct task_struct *tsk = current; |
| struct cfq_io_cq *cic; |
| struct cfq_queue *cfqq; |
| |
| cic = cfq_cic_lookup(cfqd, tsk->io_context); |
| if (!cic) |
| return NULL; |
| |
| cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
| if (cfqq) { |
| sector_t sector = bio->bi_sector + bio_sectors(bio); |
| |
| return elv_rb_find(&cfqq->sort_list, sector); |
| } |
| |
| return NULL; |
| } |
| |
| static void cfq_activate_request(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| |
| cfqd->rq_in_driver++; |
| cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d", |
| cfqd->rq_in_driver); |
| |
| cfqd->last_position = blk_rq_pos(rq) + blk_rq_sectors(rq); |
| } |
| |
| static void cfq_deactivate_request(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| |
| WARN_ON(!cfqd->rq_in_driver); |
| cfqd->rq_in_driver--; |
| cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d", |
| cfqd->rq_in_driver); |
| } |
| |
| static void cfq_remove_request(struct request *rq) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| |
| if (cfqq->next_rq == rq) |
| cfqq->next_rq = cfq_find_next_rq(cfqq->cfqd, cfqq, rq); |
| |
| list_del_init(&rq->queuelist); |
| cfq_del_rq_rb(rq); |
| |
| cfqq->cfqd->rq_queued--; |
| cfq_blkiocg_update_io_remove_stats(&(RQ_CFQG(rq))->blkg, |
| rq_data_dir(rq), rq_is_sync(rq)); |
| if (rq->cmd_flags & REQ_PRIO) { |
| WARN_ON(!cfqq->prio_pending); |
| cfqq->prio_pending--; |
| } |
| } |
| |
| static int cfq_merge(struct request_queue *q, struct request **req, |
| struct bio *bio) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct request *__rq; |
| |
| __rq = cfq_find_rq_fmerge(cfqd, bio); |
| if (__rq && elv_rq_merge_ok(__rq, bio)) { |
| *req = __rq; |
| return ELEVATOR_FRONT_MERGE; |
| } |
| |
| return ELEVATOR_NO_MERGE; |
| } |
| |
| static void cfq_merged_request(struct request_queue *q, struct request *req, |
| int type) |
| { |
| if (type == ELEVATOR_FRONT_MERGE) { |
| struct cfq_queue *cfqq = RQ_CFQQ(req); |
| |
| cfq_reposition_rq_rb(cfqq, req); |
| } |
| } |
| |
| static void cfq_bio_merged(struct request_queue *q, struct request *req, |
| struct bio *bio) |
| { |
| cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(req))->blkg, |
| bio_data_dir(bio), cfq_bio_sync(bio)); |
| } |
| |
| static void |
| cfq_merged_requests(struct request_queue *q, struct request *rq, |
| struct request *next) |
| { |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| |
| /* |
| * reposition in fifo if next is older than rq |
| */ |
| if (!list_empty(&rq->queuelist) && !list_empty(&next->queuelist) && |
| time_before(rq_fifo_time(next), rq_fifo_time(rq))) { |
| list_move(&rq->queuelist, &next->queuelist); |
| rq_set_fifo_time(rq, rq_fifo_time(next)); |
| } |
| |
| if (cfqq->next_rq == next) |
| cfqq->next_rq = rq; |
| cfq_remove_request(next); |
| cfq_blkiocg_update_io_merged_stats(&(RQ_CFQG(rq))->blkg, |
| rq_data_dir(next), rq_is_sync(next)); |
| |
| cfqq = RQ_CFQQ(next); |
| /* |
| * all requests of this queue are merged to other queues, delete it |
| * from the service tree. If it's the active_queue, |
| * cfq_dispatch_requests() will choose to expire it or do idle |
| */ |
| if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list) && |
| cfqq != cfqd->active_queue) |
| cfq_del_cfqq_rr(cfqd, cfqq); |
| } |
| |
| static int cfq_allow_merge(struct request_queue *q, struct request *rq, |
| struct bio *bio) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_io_cq *cic; |
| struct cfq_queue *cfqq; |
| |
| /* |
| * Disallow merge of a sync bio into an async request. |
| */ |
| if (cfq_bio_sync(bio) && !rq_is_sync(rq)) |
| return false; |
| |
| /* |
| * Lookup the cfqq that this bio will be queued with and allow |
| * merge only if rq is queued there. This function can be called |
| * from plug merge without queue_lock. In such cases, ioc of @rq |
| * and %current are guaranteed to be equal. Avoid lookup which |
| * requires queue_lock by using @rq's cic. |
| */ |
| if (current->io_context == RQ_CIC(rq)->icq.ioc) { |
| cic = RQ_CIC(rq); |
| } else { |
| cic = cfq_cic_lookup(cfqd, current->io_context); |
| if (!cic) |
| return false; |
| } |
| |
| cfqq = cic_to_cfqq(cic, cfq_bio_sync(bio)); |
| return cfqq == RQ_CFQQ(rq); |
| } |
| |
| static inline void cfq_del_timer(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| del_timer(&cfqd->idle_slice_timer); |
| cfq_blkiocg_update_idle_time_stats(&cfqq->cfqg->blkg); |
| } |
| |
| static void __cfq_set_active_queue(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| if (cfqq) { |
| cfq_log_cfqq(cfqd, cfqq, "set_active wl_prio:%d wl_type:%d", |
| cfqd->serving_prio, cfqd->serving_type); |
| cfq_blkiocg_update_avg_queue_size_stats(&cfqq->cfqg->blkg); |
| cfqq->slice_start = 0; |
| cfqq->dispatch_start = jiffies; |
| cfqq->allocated_slice = 0; |
| cfqq->slice_end = 0; |
| cfqq->slice_dispatch = 0; |
| cfqq->nr_sectors = 0; |
| |
| cfq_clear_cfqq_wait_request(cfqq); |
| cfq_clear_cfqq_must_dispatch(cfqq); |
| cfq_clear_cfqq_must_alloc_slice(cfqq); |
| cfq_clear_cfqq_fifo_expire(cfqq); |
| cfq_mark_cfqq_slice_new(cfqq); |
| |
| cfq_del_timer(cfqd, cfqq); |
| } |
| |
| cfqd->active_queue = cfqq; |
| } |
| |
| /* |
| * current cfqq expired its slice (or was too idle), select new one |
| */ |
| static void |
| __cfq_slice_expired(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| bool timed_out) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "slice expired t=%d", timed_out); |
| |
| if (cfq_cfqq_wait_request(cfqq)) |
| cfq_del_timer(cfqd, cfqq); |
| |
| cfq_clear_cfqq_wait_request(cfqq); |
| cfq_clear_cfqq_wait_busy(cfqq); |
| |
| /* |
| * If this cfqq is shared between multiple processes, check to |
| * make sure that those processes are still issuing I/Os within |
| * the mean seek distance. If not, it may be time to break the |
| * queues apart again. |
| */ |
| if (cfq_cfqq_coop(cfqq) && CFQQ_SEEKY(cfqq)) |
| cfq_mark_cfqq_split_coop(cfqq); |
| |
| /* |
| * store what was left of this slice, if the queue idled/timed out |
| */ |
| if (timed_out) { |
| if (cfq_cfqq_slice_new(cfqq)) |
| cfqq->slice_resid = cfq_scaled_cfqq_slice(cfqd, cfqq); |
| else |
| cfqq->slice_resid = cfqq->slice_end - jiffies; |
| cfq_log_cfqq(cfqd, cfqq, "resid=%ld", cfqq->slice_resid); |
| } |
| |
| cfq_group_served(cfqd, cfqq->cfqg, cfqq); |
| |
| if (cfq_cfqq_on_rr(cfqq) && RB_EMPTY_ROOT(&cfqq->sort_list)) |
| cfq_del_cfqq_rr(cfqd, cfqq); |
| |
| cfq_resort_rr_list(cfqd, cfqq); |
| |
| if (cfqq == cfqd->active_queue) |
| cfqd->active_queue = NULL; |
| |
| if (cfqd->active_cic) { |
| put_io_context(cfqd->active_cic->icq.ioc, cfqd->queue); |
| cfqd->active_cic = NULL; |
| } |
| } |
| |
| static inline void cfq_slice_expired(struct cfq_data *cfqd, bool timed_out) |
| { |
| struct cfq_queue *cfqq = cfqd->active_queue; |
| |
| if (cfqq) |
| __cfq_slice_expired(cfqd, cfqq, timed_out); |
| } |
| |
| /* |
| * Get next queue for service. Unless we have a queue preemption, |
| * we'll simply select the first cfqq in the service tree. |
| */ |
| static struct cfq_queue *cfq_get_next_queue(struct cfq_data *cfqd) |
| { |
| struct cfq_rb_root *service_tree = |
| service_tree_for(cfqd->serving_group, cfqd->serving_prio, |
| cfqd->serving_type); |
| |
| if (!cfqd->rq_queued) |
| return NULL; |
| |
| /* There is nothing to dispatch */ |
| if (!service_tree) |
| return NULL; |
| if (RB_EMPTY_ROOT(&service_tree->rb)) |
| return NULL; |
| return cfq_rb_first(service_tree); |
| } |
| |
| static struct cfq_queue *cfq_get_next_queue_forced(struct cfq_data *cfqd) |
| { |
| struct cfq_group *cfqg; |
| struct cfq_queue *cfqq; |
| int i, j; |
| struct cfq_rb_root *st; |
| |
| if (!cfqd->rq_queued) |
| return NULL; |
| |
| cfqg = cfq_get_next_cfqg(cfqd); |
| if (!cfqg) |
| return NULL; |
| |
| for_each_cfqg_st(cfqg, i, j, st) |
| if ((cfqq = cfq_rb_first(st)) != NULL) |
| return cfqq; |
| return NULL; |
| } |
| |
| /* |
| * Get and set a new active queue for service. |
| */ |
| static struct cfq_queue *cfq_set_active_queue(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| if (!cfqq) |
| cfqq = cfq_get_next_queue(cfqd); |
| |
| __cfq_set_active_queue(cfqd, cfqq); |
| return cfqq; |
| } |
| |
| static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd, |
| struct request *rq) |
| { |
| if (blk_rq_pos(rq) >= cfqd->last_position) |
| return blk_rq_pos(rq) - cfqd->last_position; |
| else |
| return cfqd->last_position - blk_rq_pos(rq); |
| } |
| |
| static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct request *rq) |
| { |
| return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR; |
| } |
| |
| static struct cfq_queue *cfqq_close(struct cfq_data *cfqd, |
| struct cfq_queue *cur_cfqq) |
| { |
| struct rb_root *root = &cfqd->prio_trees[cur_cfqq->org_ioprio]; |
| struct rb_node *parent, *node; |
| struct cfq_queue *__cfqq; |
| sector_t sector = cfqd->last_position; |
| |
| if (RB_EMPTY_ROOT(root)) |
| return NULL; |
| |
| /* |
| * First, if we find a request starting at the end of the last |
| * request, choose it. |
| */ |
| __cfqq = cfq_prio_tree_lookup(cfqd, root, sector, &parent, NULL); |
| if (__cfqq) |
| return __cfqq; |
| |
| /* |
| * If the exact sector wasn't found, the parent of the NULL leaf |
| * will contain the closest sector. |
| */ |
| __cfqq = rb_entry(parent, struct cfq_queue, p_node); |
| if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
| return __cfqq; |
| |
| if (blk_rq_pos(__cfqq->next_rq) < sector) |
| node = rb_next(&__cfqq->p_node); |
| else |
| node = rb_prev(&__cfqq->p_node); |
| if (!node) |
| return NULL; |
| |
| __cfqq = rb_entry(node, struct cfq_queue, p_node); |
| if (cfq_rq_close(cfqd, cur_cfqq, __cfqq->next_rq)) |
| return __cfqq; |
| |
| return NULL; |
| } |
| |
| /* |
| * cfqd - obvious |
| * cur_cfqq - passed in so that we don't decide that the current queue is |
| * closely cooperating with itself. |
| * |
| * So, basically we're assuming that that cur_cfqq has dispatched at least |
| * one request, and that cfqd->last_position reflects a position on the disk |
| * associated with the I/O issued by cur_cfqq. I'm not sure this is a valid |
| * assumption. |
| */ |
| static struct cfq_queue *cfq_close_cooperator(struct cfq_data *cfqd, |
| struct cfq_queue *cur_cfqq) |
| { |
| struct cfq_queue *cfqq; |
| |
| if (cfq_class_idle(cur_cfqq)) |
| return NULL; |
| if (!cfq_cfqq_sync(cur_cfqq)) |
| return NULL; |
| if (CFQQ_SEEKY(cur_cfqq)) |
| return NULL; |
| |
| /* |
| * Don't search priority tree if it's the only queue in the group. |
| */ |
| if (cur_cfqq->cfqg->nr_cfqq == 1) |
| return NULL; |
| |
| /* |
| * We should notice if some of the queues are cooperating, eg |
| * working closely on the same area of the disk. In that case, |
| * we can group them together and don't waste time idling. |
| */ |
| cfqq = cfqq_close(cfqd, cur_cfqq); |
| if (!cfqq) |
| return NULL; |
| |
| /* If new queue belongs to different cfq_group, don't choose it */ |
| if (cur_cfqq->cfqg != cfqq->cfqg) |
| return NULL; |
| |
| /* |
| * It only makes sense to merge sync queues. |
| */ |
| if (!cfq_cfqq_sync(cfqq)) |
| return NULL; |
| if (CFQQ_SEEKY(cfqq)) |
| return NULL; |
| |
| /* |
| * Do not merge queues of different priority classes |
| */ |
| if (cfq_class_rt(cfqq) != cfq_class_rt(cur_cfqq)) |
| return NULL; |
| |
| return cfqq; |
| } |
| |
| /* |
| * Determine whether we should enforce idle window for this queue. |
| */ |
| |
| static bool cfq_should_idle(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| enum wl_prio_t prio = cfqq_prio(cfqq); |
| struct cfq_rb_root *service_tree = cfqq->service_tree; |
| |
| BUG_ON(!service_tree); |
| BUG_ON(!service_tree->count); |
| |
| if (!cfqd->cfq_slice_idle) |
| return false; |
| |
| /* We never do for idle class queues. */ |
| if (prio == IDLE_WORKLOAD) |
| return false; |
| |
| /* We do for queues that were marked with idle window flag. */ |
| if (cfq_cfqq_idle_window(cfqq) && |
| !(blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)) |
| return true; |
| |
| /* |
| * Otherwise, we do only if they are the last ones |
| * in their service tree. |
| */ |
| if (service_tree->count == 1 && cfq_cfqq_sync(cfqq) && |
| !cfq_io_thinktime_big(cfqd, &service_tree->ttime, false)) |
| return true; |
| cfq_log_cfqq(cfqd, cfqq, "Not idling. st->count:%d", |
| service_tree->count); |
| return false; |
| } |
| |
| static void cfq_arm_slice_timer(struct cfq_data *cfqd) |
| { |
| struct cfq_queue *cfqq = cfqd->active_queue; |
| struct cfq_io_cq *cic; |
| unsigned long sl, group_idle = 0; |
| |
| /* |
| * SSD device without seek penalty, disable idling. But only do so |
| * for devices that support queuing, otherwise we still have a problem |
| * with sync vs async workloads. |
| */ |
| if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag) |
| return; |
| |
| WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list)); |
| WARN_ON(cfq_cfqq_slice_new(cfqq)); |
| |
| /* |
| * idle is disabled, either manually or by past process history |
| */ |
| if (!cfq_should_idle(cfqd, cfqq)) { |
| /* no queue idling. Check for group idling */ |
| if (cfqd->cfq_group_idle) |
| group_idle = cfqd->cfq_group_idle; |
| else |
| return; |
| } |
| |
| /* |
| * still active requests from this queue, don't idle |
| */ |
| if (cfqq->dispatched) |
| return; |
| |
| /* |
| * task has exited, don't wait |
| */ |
| cic = cfqd->active_cic; |
| if (!cic || !atomic_read(&cic->icq.ioc->nr_tasks)) |
| return; |
| |
| /* |
| * If our average think time is larger than the remaining time |
| * slice, then don't idle. This avoids overrunning the allotted |
| * time slice. |
| */ |
| if (sample_valid(cic->ttime.ttime_samples) && |
| (cfqq->slice_end - jiffies < cic->ttime.ttime_mean)) { |
| cfq_log_cfqq(cfqd, cfqq, "Not idling. think_time:%lu", |
| cic->ttime.ttime_mean); |
| return; |
| } |
| |
| /* There are other queues in the group, don't do group idle */ |
| if (group_idle && cfqq->cfqg->nr_cfqq > 1) |
| return; |
| |
| cfq_mark_cfqq_wait_request(cfqq); |
| |
| if (group_idle) |
| sl = cfqd->cfq_group_idle; |
| else |
| sl = cfqd->cfq_slice_idle; |
| |
| mod_timer(&cfqd->idle_slice_timer, jiffies + sl); |
| cfq_blkiocg_update_set_idle_time_stats(&cfqq->cfqg->blkg); |
| cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu group_idle: %d", sl, |
| group_idle ? 1 : 0); |
| } |
| |
| /* |
| * Move request from internal lists to the request queue dispatch list. |
| */ |
| static void cfq_dispatch_insert(struct request_queue *q, struct request *rq) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_queue *cfqq = RQ_CFQQ(rq); |
| |
| cfq_log_cfqq(cfqd, cfqq, "dispatch_insert"); |
| |
| cfqq->next_rq = cfq_find_next_rq(cfqd, cfqq, rq); |
| cfq_remove_request(rq); |
| cfqq->dispatched++; |
| (RQ_CFQG(rq))->dispatched++; |
| elv_dispatch_sort(q, rq); |
| |
| cfqd->rq_in_flight[cfq_cfqq_sync(cfqq)]++; |
| cfqq->nr_sectors += blk_rq_sectors(rq); |
| cfq_blkiocg_update_dispatch_stats(&cfqq->cfqg->blkg, blk_rq_bytes(rq), |
| rq_data_dir(rq), rq_is_sync(rq)); |
| } |
| |
| /* |
| * return expired entry, or NULL to just start from scratch in rbtree |
| */ |
| static struct request *cfq_check_fifo(struct cfq_queue *cfqq) |
| { |
| struct request *rq = NULL; |
| |
| if (cfq_cfqq_fifo_expire(cfqq)) |
| return NULL; |
| |
| cfq_mark_cfqq_fifo_expire(cfqq); |
| |
| if (list_empty(&cfqq->fifo)) |
| return NULL; |
| |
| rq = rq_entry_fifo(cfqq->fifo.next); |
| if (time_before(jiffies, rq_fifo_time(rq))) |
| rq = NULL; |
| |
| cfq_log_cfqq(cfqq->cfqd, cfqq, "fifo=%p", rq); |
| return rq; |
| } |
| |
| static inline int |
| cfq_prio_to_maxrq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| const int base_rq = cfqd->cfq_slice_async_rq; |
| |
| WARN_ON(cfqq->ioprio >= IOPRIO_BE_NR); |
| |
| return 2 * base_rq * (IOPRIO_BE_NR - cfqq->ioprio); |
| } |
| |
| /* |
| * Must be called with the queue_lock held. |
| */ |
| static int cfqq_process_refs(struct cfq_queue *cfqq) |
| { |
| int process_refs, io_refs; |
| |
| io_refs = cfqq->allocated[READ] + cfqq->allocated[WRITE]; |
| process_refs = cfqq->ref - io_refs; |
| BUG_ON(process_refs < 0); |
| return process_refs; |
| } |
| |
| static void cfq_setup_merge(struct cfq_queue *cfqq, struct cfq_queue *new_cfqq) |
| { |
| int process_refs, new_process_refs; |
| struct cfq_queue *__cfqq; |
| |
| /* |
| * If there are no process references on the new_cfqq, then it is |
| * unsafe to follow the ->new_cfqq chain as other cfqq's in the |
| * chain may have dropped their last reference (not just their |
| * last process reference). |
| */ |
| if (!cfqq_process_refs(new_cfqq)) |
| return; |
| |
| /* Avoid a circular list and skip interim queue merges */ |
| while ((__cfqq = new_cfqq->new_cfqq)) { |
| if (__cfqq == cfqq) |
| return; |
| new_cfqq = __cfqq; |
| } |
| |
| process_refs = cfqq_process_refs(cfqq); |
| new_process_refs = cfqq_process_refs(new_cfqq); |
| /* |
| * If the process for the cfqq has gone away, there is no |
| * sense in merging the queues. |
| */ |
| if (process_refs == 0 || new_process_refs == 0) |
| return; |
| |
| /* |
| * Merge in the direction of the lesser amount of work. |
| */ |
| if (new_process_refs >= process_refs) { |
| cfqq->new_cfqq = new_cfqq; |
| new_cfqq->ref += process_refs; |
| } else { |
| new_cfqq->new_cfqq = cfqq; |
| cfqq->ref += new_process_refs; |
| } |
| } |
| |
| static enum wl_type_t cfq_choose_wl(struct cfq_data *cfqd, |
| struct cfq_group *cfqg, enum wl_prio_t prio) |
| { |
| struct cfq_queue *queue; |
| int i; |
| bool key_valid = false; |
| unsigned long lowest_key = 0; |
| enum wl_type_t cur_best = SYNC_NOIDLE_WORKLOAD; |
| |
| for (i = 0; i <= SYNC_WORKLOAD; ++i) { |
| /* select the one with lowest rb_key */ |
| queue = cfq_rb_first(service_tree_for(cfqg, prio, i)); |
| if (queue && |
| (!key_valid || time_before(queue->rb_key, lowest_key))) { |
| lowest_key = queue->rb_key; |
| cur_best = i; |
| key_valid = true; |
| } |
| } |
| |
| return cur_best; |
| } |
| |
| static void choose_service_tree(struct cfq_data *cfqd, struct cfq_group *cfqg) |
| { |
| unsigned slice; |
| unsigned count; |
| struct cfq_rb_root *st; |
| unsigned group_slice; |
| enum wl_prio_t original_prio = cfqd->serving_prio; |
| |
| /* Choose next priority. RT > BE > IDLE */ |
| if (cfq_group_busy_queues_wl(RT_WORKLOAD, cfqd, cfqg)) |
| cfqd->serving_prio = RT_WORKLOAD; |
| else if (cfq_group_busy_queues_wl(BE_WORKLOAD, cfqd, cfqg)) |
| cfqd->serving_prio = BE_WORKLOAD; |
| else { |
| cfqd->serving_prio = IDLE_WORKLOAD; |
| cfqd->workload_expires = jiffies + 1; |
| return; |
| } |
| |
| if (original_prio != cfqd->serving_prio) |
| goto new_workload; |
| |
| /* |
| * For RT and BE, we have to choose also the type |
| * (SYNC, SYNC_NOIDLE, ASYNC), and to compute a workload |
| * expiration time |
| */ |
| st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); |
| count = st->count; |
| |
| /* |
| * check workload expiration, and that we still have other queues ready |
| */ |
| if (count && !time_after(jiffies, cfqd->workload_expires)) |
| return; |
| |
| new_workload: |
| /* otherwise select new workload type */ |
| cfqd->serving_type = |
| cfq_choose_wl(cfqd, cfqg, cfqd->serving_prio); |
| st = service_tree_for(cfqg, cfqd->serving_prio, cfqd->serving_type); |
| count = st->count; |
| |
| /* |
| * the workload slice is computed as a fraction of target latency |
| * proportional to the number of queues in that workload, over |
| * all the queues in the same priority class |
| */ |
| group_slice = cfq_group_slice(cfqd, cfqg); |
| |
| slice = group_slice * count / |
| max_t(unsigned, cfqg->busy_queues_avg[cfqd->serving_prio], |
| cfq_group_busy_queues_wl(cfqd->serving_prio, cfqd, cfqg)); |
| |
| if (cfqd->serving_type == ASYNC_WORKLOAD) { |
| unsigned int tmp; |
| |
| /* |
| * Async queues are currently system wide. Just taking |
| * proportion of queues with-in same group will lead to higher |
| * async ratio system wide as generally root group is going |
| * to have higher weight. A more accurate thing would be to |
| * calculate system wide asnc/sync ratio. |
| */ |
| tmp = cfq_target_latency * cfqg_busy_async_queues(cfqd, cfqg); |
| tmp = tmp/cfqd->busy_queues; |
| slice = min_t(unsigned, slice, tmp); |
| |
| /* async workload slice is scaled down according to |
| * the sync/async slice ratio. */ |
| slice = slice * cfqd->cfq_slice[0] / cfqd->cfq_slice[1]; |
| } else |
| /* sync workload slice is at least 2 * cfq_slice_idle */ |
| slice = max(slice, 2 * cfqd->cfq_slice_idle); |
| |
| slice = max_t(unsigned, slice, CFQ_MIN_TT); |
| cfq_log(cfqd, "workload slice:%d", slice); |
| cfqd->workload_expires = jiffies + slice; |
| } |
| |
| static struct cfq_group *cfq_get_next_cfqg(struct cfq_data *cfqd) |
| { |
| struct cfq_rb_root *st = &cfqd->grp_service_tree; |
| struct cfq_group *cfqg; |
| |
| if (RB_EMPTY_ROOT(&st->rb)) |
| return NULL; |
| cfqg = cfq_rb_first_group(st); |
| update_min_vdisktime(st); |
| return cfqg; |
| } |
| |
| static void cfq_choose_cfqg(struct cfq_data *cfqd) |
| { |
| struct cfq_group *cfqg = cfq_get_next_cfqg(cfqd); |
| |
| cfqd->serving_group = cfqg; |
| |
| /* Restore the workload type data */ |
| if (cfqg->saved_workload_slice) { |
| cfqd->workload_expires = jiffies + cfqg->saved_workload_slice; |
| cfqd->serving_type = cfqg->saved_workload; |
| cfqd->serving_prio = cfqg->saved_serving_prio; |
| } else |
| cfqd->workload_expires = jiffies - 1; |
| |
| choose_service_tree(cfqd, cfqg); |
| } |
| |
| /* |
| * Select a queue for service. If we have a current active queue, |
| * check whether to continue servicing it, or retrieve and set a new one. |
| */ |
| static struct cfq_queue *cfq_select_queue(struct cfq_data *cfqd) |
| { |
| struct cfq_queue *cfqq, *new_cfqq = NULL; |
| |
| cfqq = cfqd->active_queue; |
| if (!cfqq) |
| goto new_queue; |
| |
| if (!cfqd->rq_queued) |
| return NULL; |
| |
| /* |
| * We were waiting for group to get backlogged. Expire the queue |
| */ |
| if (cfq_cfqq_wait_busy(cfqq) && !RB_EMPTY_ROOT(&cfqq->sort_list)) |
| goto expire; |
| |
| /* |
| * The active queue has run out of time, expire it and select new. |
| */ |
| if (cfq_slice_used(cfqq) && !cfq_cfqq_must_dispatch(cfqq)) { |
| /* |
| * If slice had not expired at the completion of last request |
| * we might not have turned on wait_busy flag. Don't expire |
| * the queue yet. Allow the group to get backlogged. |
| * |
| * The very fact that we have used the slice, that means we |
| * have been idling all along on this queue and it should be |
| * ok to wait for this request to complete. |
| */ |
| if (cfqq->cfqg->nr_cfqq == 1 && RB_EMPTY_ROOT(&cfqq->sort_list) |
| && cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { |
| cfqq = NULL; |
| goto keep_queue; |
| } else |
| goto check_group_idle; |
| } |
| |
| /* |
| * The active queue has requests and isn't expired, allow it to |
| * dispatch. |
| */ |
| if (!RB_EMPTY_ROOT(&cfqq->sort_list)) |
| goto keep_queue; |
| |
| /* |
| * If another queue has a request waiting within our mean seek |
| * distance, let it run. The expire code will check for close |
| * cooperators and put the close queue at the front of the service |
| * tree. If possible, merge the expiring queue with the new cfqq. |
| */ |
| new_cfqq = cfq_close_cooperator(cfqd, cfqq); |
| if (new_cfqq) { |
| if (!cfqq->new_cfqq) |
| cfq_setup_merge(cfqq, new_cfqq); |
| goto expire; |
| } |
| |
| /* |
| * No requests pending. If the active queue still has requests in |
| * flight or is idling for a new request, allow either of these |
| * conditions to happen (or time out) before selecting a new queue. |
| */ |
| if (timer_pending(&cfqd->idle_slice_timer)) { |
| cfqq = NULL; |
| goto keep_queue; |
| } |
| |
| /* |
| * This is a deep seek queue, but the device is much faster than |
| * the queue can deliver, don't idle |
| **/ |
| if (CFQQ_SEEKY(cfqq) && cfq_cfqq_idle_window(cfqq) && |
| (cfq_cfqq_slice_new(cfqq) || |
| (cfqq->slice_end - jiffies > jiffies - cfqq->slice_start))) { |
| cfq_clear_cfqq_deep(cfqq); |
| cfq_clear_cfqq_idle_window(cfqq); |
| } |
| |
| if (cfqq->dispatched && cfq_should_idle(cfqd, cfqq)) { |
| cfqq = NULL; |
| goto keep_queue; |
| } |
| |
| /* |
| * If group idle is enabled and there are requests dispatched from |
| * this group, wait for requests to complete. |
| */ |
| check_group_idle: |
| if (cfqd->cfq_group_idle && cfqq->cfqg->nr_cfqq == 1 && |
| cfqq->cfqg->dispatched && |
| !cfq_io_thinktime_big(cfqd, &cfqq->cfqg->ttime, true)) { |
| cfqq = NULL; |
| goto keep_queue; |
| } |
| |
| expire: |
| cfq_slice_expired(cfqd, 0); |
| new_queue: |
| /* |
| * Current queue expired. Check if we have to switch to a new |
| * service tree |
| */ |
| if (!new_cfqq) |
| cfq_choose_cfqg(cfqd); |
| |
| cfqq = cfq_set_active_queue(cfqd, new_cfqq); |
| keep_queue: |
| return cfqq; |
| } |
| |
| static int __cfq_forced_dispatch_cfqq(struct cfq_queue *cfqq) |
| { |
| int dispatched = 0; |
| |
| while (cfqq->next_rq) { |
| cfq_dispatch_insert(cfqq->cfqd->queue, cfqq->next_rq); |
| dispatched++; |
| } |
| |
| BUG_ON(!list_empty(&cfqq->fifo)); |
| |
| /* By default cfqq is not expired if it is empty. Do it explicitly */ |
| __cfq_slice_expired(cfqq->cfqd, cfqq, 0); |
| return dispatched; |
| } |
| |
| /* |
| * Drain our current requests. Used for barriers and when switching |
| * io schedulers on-the-fly. |
| */ |
| static int cfq_forced_dispatch(struct cfq_data *cfqd) |
| { |
| struct cfq_queue *cfqq; |
| int dispatched = 0; |
| |
| /* Expire the timeslice of the current active queue first */ |
| cfq_slice_expired(cfqd, 0); |
| while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL) { |
| __cfq_set_active_queue(cfqd, cfqq); |
| dispatched += __cfq_forced_dispatch_cfqq(cfqq); |
| } |
| |
| BUG_ON(cfqd->busy_queues); |
| |
| cfq_log(cfqd, "forced_dispatch=%d", dispatched); |
| return dispatched; |
| } |
| |
| static inline bool cfq_slice_used_soon(struct cfq_data *cfqd, |
| struct cfq_queue *cfqq) |
| { |
| /* the queue hasn't finished any request, can't estimate */ |
| if (cfq_cfqq_slice_new(cfqq)) |
| return true; |
| if (time_after(jiffies + cfqd->cfq_slice_idle * cfqq->dispatched, |
| cfqq->slice_end)) |
| return true; |
| |
| return false; |
| } |
| |
| static bool cfq_may_dispatch(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| unsigned int max_dispatch; |
| |
| /* |
| * Drain async requests before we start sync IO |
| */ |
| if (cfq_should_idle(cfqd, cfqq) && cfqd->rq_in_flight[BLK_RW_ASYNC]) |
| return false; |
| |
| /* |
| * If this is an async queue and we have sync IO in flight, let it wait |
| */ |
| if (cfqd->rq_in_flight[BLK_RW_SYNC] && !cfq_cfqq_sync(cfqq)) |
| return false; |
| |
| max_dispatch = max_t(unsigned int, cfqd->cfq_quantum / 2, 1); |
| if (cfq_class_idle(cfqq)) |
| max_dispatch = 1; |
| |
| /* |
| * Does this cfqq already have too much IO in flight? |
| */ |
| if (cfqq->dispatched >= max_dispatch) { |
| bool promote_sync = false; |
| /* |
| * idle queue must always only have a single IO in flight |
| */ |
| if (cfq_class_idle(cfqq)) |
| return false; |
| |
| /* |
| * If there is only one sync queue |
| * we can ignore async queue here and give the sync |
| * queue no dispatch limit. The reason is a sync queue can |
| * preempt async queue, limiting the sync queue doesn't make |
| * sense. This is useful for aiostress test. |
| */ |
| if (cfq_cfqq_sync(cfqq) && cfqd->busy_sync_queues == 1) |
| promote_sync = true; |
| |
| /* |
| * We have other queues, don't allow more IO from this one |
| */ |
| if (cfqd->busy_queues > 1 && cfq_slice_used_soon(cfqd, cfqq) && |
| !promote_sync) |
| return false; |
| |
| /* |
| * Sole queue user, no limit |
| */ |
| if (cfqd->busy_queues == 1 || promote_sync) |
| max_dispatch = -1; |
| else |
| /* |
| * Normally we start throttling cfqq when cfq_quantum/2 |
| * requests have been dispatched. But we can drive |
| * deeper queue depths at the beginning of slice |
| * subjected to upper limit of cfq_quantum. |
| * */ |
| max_dispatch = cfqd->cfq_quantum; |
| } |
| |
| /* |
| * Async queues must wait a bit before being allowed dispatch. |
| * We also ramp up the dispatch depth gradually for async IO, |
| * based on the last sync IO we serviced |
| */ |
| if (!cfq_cfqq_sync(cfqq) && cfqd->cfq_latency) { |
| unsigned long last_sync = jiffies - cfqd->last_delayed_sync; |
| unsigned int depth; |
| |
| depth = last_sync / cfqd->cfq_slice[1]; |
| if (!depth && !cfqq->dispatched) |
| depth = 1; |
| if (depth < max_dispatch) |
| max_dispatch = depth; |
| } |
| |
| /* |
| * If we're below the current max, allow a dispatch |
| */ |
| return cfqq->dispatched < max_dispatch; |
| } |
| |
| /* |
| * Dispatch a request from cfqq, moving them to the request queue |
| * dispatch list. |
| */ |
| static bool cfq_dispatch_request(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| struct request *rq; |
| |
| BUG_ON(RB_EMPTY_ROOT(&cfqq->sort_list)); |
| |
| if (!cfq_may_dispatch(cfqd, cfqq)) |
| return false; |
| |
| /* |
| * follow expired path, else get first next available |
| */ |
| rq = cfq_check_fifo(cfqq); |
| if (!rq) |
| rq = cfqq->next_rq; |
| |
| /* |
| * insert request into driver dispatch list |
| */ |
| cfq_dispatch_insert(cfqd->queue, rq); |
| |
| if (!cfqd->active_cic) { |
| struct cfq_io_cq *cic = RQ_CIC(rq); |
| |
| atomic_long_inc(&cic->icq.ioc->refcount); |
| cfqd->active_cic = cic; |
| } |
| |
| return true; |
| } |
| |
| /* |
| * Find the cfqq that we need to service and move a request from that to the |
| * dispatch list |
| */ |
| static int cfq_dispatch_requests(struct request_queue *q, int force) |
| { |
| struct cfq_data *cfqd = q->elevator->elevator_data; |
| struct cfq_queue *cfqq; |
| |
| if (!cfqd->busy_queues) |
| return 0; |
| |
| if (unlikely(force)) |
| return cfq_forced_dispatch(cfqd); |
| |
| cfqq = cfq_select_queue(cfqd); |
| if (!cfqq) |
| return 0; |
| |
| /* |
| * Dispatch a request from this cfqq, if it is allowed |
| */ |
| if (!cfq_dispatch_request(cfqd, cfqq)) |
| return 0; |
| |
| cfqq->slice_dispatch++; |
| cfq_clear_cfqq_must_dispatch(cfqq); |
| |
| /* |
| * expire an async queue immediately if it has used up its slice. idle |
| * queue always expire after 1 dispatch round. |
| */ |
| if (cfqd->busy_queues > 1 && ((!cfq_cfqq_sync(cfqq) && |
| cfqq->slice_dispatch >= cfq_prio_to_maxrq(cfqd, cfqq)) || |
| cfq_class_idle(cfqq))) { |
| cfqq->slice_end = jiffies + 1; |
| cfq_slice_expired(cfqd, 0); |
| } |
| |
| cfq_log_cfqq(cfqd, cfqq, "dispatched a request"); |
| return 1; |
| } |
| |
| /* |
| * task holds one reference to the queue, dropped when task exits. each rq |
| * in-flight on this queue also holds a reference, dropped when rq is freed. |
| * |
| * Each cfq queue took a reference on the parent group. Drop it now. |
| * queue lock must be held here. |
| */ |
| static void cfq_put_queue(struct cfq_queue *cfqq) |
| { |
| struct cfq_data *cfqd = cfqq->cfqd; |
| struct cfq_group *cfqg; |
| |
| BUG_ON(cfqq->ref <= 0); |
| |
| cfqq->ref--; |
| if (cfqq->ref) |
| return; |
| |
| cfq_log_cfqq(cfqd, cfqq, "put_queue"); |
| BUG_ON(rb_first(&cfqq->sort_list)); |
| BUG_ON(cfqq->allocated[READ] + cfqq->allocated[WRITE]); |
| cfqg = cfqq->cfqg; |
| |
| if (unlikely(cfqd->active_queue == cfqq)) { |
| __cfq_slice_expired(cfqd, cfqq, 0); |
| cfq_schedule_dispatch(cfqd); |
| } |
| |
| BUG_ON(cfq_cfqq_on_rr(cfqq)); |
| kmem_cache_free(cfq_pool, cfqq); |
| cfq_put_cfqg(cfqg); |
| } |
| |
| static void cfq_put_cooperator(struct cfq_queue *cfqq) |
| { |
| struct cfq_queue *__cfqq, *next; |
| |
| /* |
| * If this queue was scheduled to merge with another queue, be |
| * sure to drop the reference taken on that queue (and others in |
| * the merge chain). See cfq_setup_merge and cfq_merge_cfqqs. |
| */ |
| __cfqq = cfqq->new_cfqq; |
| while (__cfqq) { |
| if (__cfqq == cfqq) { |
| WARN(1, "cfqq->new_cfqq loop detected\n"); |
| break; |
| } |
| next = __cfqq->new_cfqq; |
| cfq_put_queue(__cfqq); |
| __cfqq = next; |
| } |
| } |
| |
| static void cfq_exit_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| if (unlikely(cfqq == cfqd->active_queue)) { |
| __cfq_slice_expired(cfqd, cfqq, 0); |
| cfq_schedule_dispatch(cfqd); |
| } |
| |
| cfq_put_cooperator(cfqq); |
| |
| cfq_put_queue(cfqq); |
| } |
| |
| static void cfq_init_icq(struct io_cq *icq) |
| { |
| struct cfq_io_cq *cic = icq_to_cic(icq); |
| |
| cic->ttime.last_end_request = jiffies; |
| } |
| |
| static void cfq_exit_icq(struct io_cq *icq) |
| { |
| struct cfq_io_cq *cic = icq_to_cic(icq); |
| struct cfq_data *cfqd = cic_to_cfqd(cic); |
| |
| if (cic->cfqq[BLK_RW_ASYNC]) { |
| cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_ASYNC]); |
| cic->cfqq[BLK_RW_ASYNC] = NULL; |
| } |
| |
| if (cic->cfqq[BLK_RW_SYNC]) { |
| cfq_exit_cfqq(cfqd, cic->cfqq[BLK_RW_SYNC]); |
| cic->cfqq[BLK_RW_SYNC] = NULL; |
| } |
| } |
| |
| static void cfq_init_prio_data(struct cfq_queue *cfqq, struct io_context *ioc) |
| { |
| struct task_struct *tsk = current; |
| int ioprio_class; |
| |
| if (!cfq_cfqq_prio_changed(cfqq)) |
| return; |
| |
| ioprio_class = IOPRIO_PRIO_CLASS(ioc->ioprio); |
| switch (ioprio_class) { |
| default: |
| printk(KERN_ERR "cfq: bad prio %x\n", ioprio_class); |
| case IOPRIO_CLASS_NONE: |
| /* |
| * no prio set, inherit CPU scheduling settings |
| */ |
| cfqq->ioprio = task_nice_ioprio(tsk); |
| cfqq->ioprio_class = task_nice_ioclass(tsk); |
| break; |
| case IOPRIO_CLASS_RT: |
| cfqq->ioprio = task_ioprio(ioc); |
| cfqq->ioprio_class = IOPRIO_CLASS_RT; |
| break; |
| case IOPRIO_CLASS_BE: |
| cfqq->ioprio = task_ioprio(ioc); |
| cfqq->ioprio_class = IOPRIO_CLASS_BE; |
| break; |
| case IOPRIO_CLASS_IDLE: |
| cfqq->ioprio_class = IOPRIO_CLASS_IDLE; |
| cfqq->ioprio = 7; |
| cfq_clear_cfqq_idle_window(cfqq); |
| break; |
| } |
| |
| /* |
| * keep track of original prio settings in case we have to temporarily |
| * elevate the priority of this queue |
| */ |
| cfqq->org_ioprio = cfqq->ioprio; |
| cfq_clear_cfqq_prio_changed(cfqq); |
| } |
| |
| static void changed_ioprio(struct cfq_io_cq *cic) |
| { |
| struct cfq_data *cfqd = cic_to_cfqd(cic); |
| struct cfq_queue *cfqq; |
| |
| if (unlikely(!cfqd)) |
| return; |
| |
| cfqq = cic->cfqq[BLK_RW_ASYNC]; |
| if (cfqq) { |
| struct cfq_queue *new_cfqq; |
| new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->icq.ioc, |
| GFP_ATOMIC); |
| if (new_cfqq) { |
| cic->cfqq[BLK_RW_ASYNC] = new_cfqq; |
| cfq_put_queue(cfqq); |
| } |
| } |
| |
| cfqq = cic->cfqq[BLK_RW_SYNC]; |
| if (cfqq) |
| cfq_mark_cfqq_prio_changed(cfqq); |
| } |
| |
| static void cfq_init_cfqq(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| pid_t pid, bool is_sync) |
| { |
| RB_CLEAR_NODE(&cfqq->rb_node); |
| RB_CLEAR_NODE(&cfqq->p_node); |
| INIT_LIST_HEAD(&cfqq->fifo); |
| |
| cfqq->ref = 0; |
| cfqq->cfqd = cfqd; |
| |
| cfq_mark_cfqq_prio_changed(cfqq); |
| |
| if (is_sync) { |
| if (!cfq_class_idle(cfqq)) |
| cfq_mark_cfqq_idle_window(cfqq); |
| cfq_mark_cfqq_sync(cfqq); |
| } |
| cfqq->pid = pid; |
| } |
| |
| #ifdef CONFIG_CFQ_GROUP_IOSCHED |
| static void changed_cgroup(struct cfq_io_cq *cic) |
| { |
| struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1); |
| struct cfq_data *cfqd = cic_to_cfqd(cic); |
| struct request_queue *q; |
| |
| if (unlikely(!cfqd)) |
| return; |
| |
| q = cfqd->queue; |
| |
| if (sync_cfqq) { |
| /* |
| * Drop reference to sync queue. A new sync queue will be |
| * assigned in new group upon arrival of a fresh request. |
| */ |
| cfq_log_cfqq(cfqd, sync_cfqq, "changed cgroup"); |
| cic_set_cfqq(cic, NULL, 1); |
| cfq_put_queue(sync_cfqq); |
| } |
| } |
| #endif /* CONFIG_CFQ_GROUP_IOSCHED */ |
| |
| static struct cfq_queue * |
| cfq_find_alloc_queue(struct cfq_data *cfqd, bool is_sync, |
| struct io_context *ioc, gfp_t gfp_mask) |
| { |
| struct cfq_queue *cfqq, *new_cfqq = NULL; |
| struct cfq_io_cq *cic; |
| struct cfq_group *cfqg; |
| |
| retry: |
| cfqg = cfq_get_cfqg(cfqd); |
| cic = cfq_cic_lookup(cfqd, ioc); |
| /* cic always exists here */ |
| cfqq = cic_to_cfqq(cic, is_sync); |
| |
| /* |
| * Always try a new alloc if we fell back to the OOM cfqq |
| * originally, since it should just be a temporary situation. |
| */ |
| if (!cfqq || cfqq == &cfqd->oom_cfqq) { |
| cfqq = NULL; |
| if (new_cfqq) { |
| cfqq = new_cfqq; |
| new_cfqq = NULL; |
| } else if (gfp_mask & __GFP_WAIT) { |
| spin_unlock_irq(cfqd->queue->queue_lock); |
| new_cfqq = kmem_cache_alloc_node(cfq_pool, |
| gfp_mask | __GFP_ZERO, |
| cfqd->queue->node); |
| spin_lock_irq(cfqd->queue->queue_lock); |
| if (new_cfqq) |
| goto retry; |
| } else { |
| cfqq = kmem_cache_alloc_node(cfq_pool, |
| gfp_mask | __GFP_ZERO, |
| cfqd->queue->node); |
| } |
| |
| if (cfqq) { |
| cfq_init_cfqq(cfqd, cfqq, current->pid, is_sync); |
| cfq_init_prio_data(cfqq, ioc); |
| cfq_link_cfqq_cfqg(cfqq, cfqg); |
| cfq_log_cfqq(cfqd, cfqq, "alloced"); |
| } else |
| cfqq = &cfqd->oom_cfqq; |
| } |
| |
| if (new_cfqq) |
| kmem_cache_free(cfq_pool, new_cfqq); |
| |
| return cfqq; |
| } |
| |
| static struct cfq_queue ** |
| cfq_async_queue_prio(struct cfq_data *cfqd, int ioprio_class, int ioprio) |
| { |
| switch (ioprio_class) { |
| case IOPRIO_CLASS_RT: |
| return &cfqd->async_cfqq[0][ioprio]; |
| case IOPRIO_CLASS_BE: |
| return &cfqd->async_cfqq[1][ioprio]; |
| case IOPRIO_CLASS_IDLE: |
| return &cfqd->async_idle_cfqq; |
| default: |
| BUG(); |
| } |
| } |
| |
| static struct cfq_queue * |
| cfq_get_queue(struct cfq_data *cfqd, bool is_sync, struct io_context *ioc, |
| gfp_t gfp_mask) |
| { |
| const int ioprio = task_ioprio(ioc); |
| const int ioprio_class = task_ioprio_class(ioc); |
| struct cfq_queue **async_cfqq = NULL; |
| struct cfq_queue *cfqq = NULL; |
| |
| if (!is_sync) { |
| async_cfqq = cfq_async_queue_prio(cfqd, ioprio_class, ioprio); |
| cfqq = *async_cfqq; |
| } |
| |
| if (!cfqq) |
| cfqq = cfq_find_alloc_queue(cfqd, is_sync, ioc, gfp_mask); |
| |
| /* |
| * pin the queue now that it's allocated, scheduler exit will prune it |
| */ |
| if (!is_sync && !(*async_cfqq)) { |
| cfqq->ref++; |
| *async_cfqq = cfqq; |
| } |
| |
| cfqq->ref++; |
| return cfqq; |
| } |
| |
| static void |
| __cfq_update_io_thinktime(struct cfq_ttime *ttime, unsigned long slice_idle) |
| { |
| unsigned long elapsed = jiffies - ttime->last_end_request; |
| elapsed = min(elapsed, 2UL * slice_idle); |
| |
| ttime->ttime_samples = (7*ttime->ttime_samples + 256) / 8; |
| ttime->ttime_total = (7*ttime->ttime_total + 256*elapsed) / 8; |
| ttime->ttime_mean = (ttime->ttime_total + 128) / ttime->ttime_samples; |
| } |
| |
| static void |
| cfq_update_io_thinktime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct cfq_io_cq *cic) |
| { |
| if (cfq_cfqq_sync(cfqq)) { |
| __cfq_update_io_thinktime(&cic->ttime, cfqd->cfq_slice_idle); |
| __cfq_update_io_thinktime(&cfqq->service_tree->ttime, |
| cfqd->cfq_slice_idle); |
| } |
| #ifdef CONFIG_CFQ_GROUP_IOSCHED |
| __cfq_update_io_thinktime(&cfqq->cfqg->ttime, cfqd->cfq_group_idle); |
| #endif |
| } |
| |
| static void |
| cfq_update_io_seektime(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct request *rq) |
| { |
| sector_t sdist = 0; |
| sector_t n_sec = blk_rq_sectors(rq); |
| if (cfqq->last_request_pos) { |
| if (cfqq->last_request_pos < blk_rq_pos(rq)) |
| sdist = blk_rq_pos(rq) - cfqq->last_request_pos; |
| else |
| sdist = cfqq->last_request_pos - blk_rq_pos(rq); |
| } |
| |
| cfqq->seek_history <<= 1; |
| if (blk_queue_nonrot(cfqd->queue)) |
| cfqq->seek_history |= (n_sec < CFQQ_SECT_THR_NONROT); |
| else |
| cfqq->seek_history |= (sdist > CFQQ_SEEK_THR); |
| } |
| |
| /* |
| * Disable idle window if the process thinks too long or seeks so much that |
| * it doesn't matter |
| */ |
| static void |
| cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct cfq_io_cq *cic) |
| { |
| int old_idle, enable_idle; |
| |
| /* |
| * Don't idle for async or idle io prio class |
| */ |
| if (!cfq_cfqq_sync(cfqq) || cfq_class_idle(cfqq)) |
| return; |
| |
| enable_idle = old_idle = cfq_cfqq_idle_window(cfqq); |
| |
| if (cfqq->queued[0] + cfqq->queued[1] >= 4) |
| cfq_mark_cfqq_deep(cfqq); |
| |
| if (cfqq->next_rq && (cfqq->next_rq->cmd_flags & REQ_NOIDLE)) |
| enable_idle = 0; |
| else if (!atomic_read(&cic->icq.ioc->nr_tasks) || |
| !cfqd->cfq_slice_idle || |
| (!cfq_cfqq_deep(cfqq) && CFQQ_SEEKY(cfqq))) |
| enable_idle = 0; |
| else if (sample_valid(cic->ttime.ttime_samples)) { |
| if (cic->ttime.ttime_mean > cfqd->cfq_slice_idle) |
| enable_idle = 0; |
| else |
| enable_idle = 1; |
| } |
| |
| if (old_idle != enable_idle) { |
| cfq_log_cfqq(cfqd, cfqq, "idle=%d", enable_idle); |
| if (enable_idle) |
| cfq_mark_cfqq_idle_window(cfqq); |
| else |
| cfq_clear_cfqq_idle_window(cfqq); |
| } |
| } |
| |
| /* |
| * Check if new_cfqq should preempt the currently active queue. Return 0 for |
| * no or if we aren't sure, a 1 will cause a preempt. |
| */ |
| static bool |
| cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq, |
| struct request *rq) |
| { |
| struct cfq_queue *cfqq; |
| |
| cfqq = cfqd->active_queue; |
| if (!cfqq) |
| return false; |
| |
| if (cfq_class_idle(new_cfqq)) |
| return false; |
| |
| if (cfq_class_idle(cfqq)) |
| return true; |
| |
| /* |
| * Don't allow a non-RT request to preempt an ongoing RT cfqq timeslice. |
| */ |
| if (cfq_class_rt(cfqq) && !cfq_class_rt(new_cfqq)) |
| return false; |
| |
| /* |
| * if the new request is sync, but the currently running queue is |
| * not, let the sync request have priority. |
| */ |
| if (rq_is_sync(rq) && !cfq_cfqq_sync(cfqq)) |
| return true; |
| |
| if (new_cfqq->cfqg != cfqq->cfqg) |
| return false; |
| |
| if (cfq_slice_used(cfqq)) |
| return true; |
| |
| /* Allow preemption only if we are idling on sync-noidle tree */ |
| if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD && |
| cfqq_type(new_cfqq) == SYNC_NOIDLE_WORKLOAD && |
| new_cfqq->service_tree->count == 2 && |
| RB_EMPTY_ROOT(&cfqq->sort_list)) |
| return true; |
| |
| /* |
| * So both queues are sync. Let the new request get disk time if |
| * it's a metadata request and the current queue is doing regular IO. |
| */ |
| if ((rq->cmd_flags & REQ_PRIO) && !cfqq->prio_pending) |
| return true; |
| |
| /* |
| * Allow an RT request to pre-empt an ongoing non-RT cfqq timeslice. |
| */ |
| if (cfq_class_rt(new_cfqq) && !cfq_class_rt(cfqq)) |
| return true; |
| |
| /* An idle queue should not be idle now for some reason */ |
| if (RB_EMPTY_ROOT(&cfqq->sort_list) && !cfq_should_idle(cfqd, cfqq)) |
| return true; |
| |
| if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq)) |
| return false; |
| |
| /* |
| * if this request is as-good as one we would expect from the |
| * current cfqq, let it preempt |
| */ |
| if (cfq_rq_close(cfqd, cfqq, rq)) |
| return true; |
| |
| return false; |
| } |
| |
| /* |
| * cfqq preempts the active queue. if we allowed preempt with no slice left, |
| * let it have half of its nominal slice. |
| */ |
| static void cfq_preempt_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq) |
| { |
| cfq_log_cfqq(cfqd, cfqq, "preempt"); |
| |
| /* |
| * workload type is changed, don't save slice, otherwise preempt |
| * doesn't happen |
| */ |
| if (cfqq_type(cfqd->active_queue) != cfqq_type(cfqq)) |
| cfqq->cfqg->saved_workload_slice = 0; |
| |
| cfq_slice_expired(cfqd, 1); |
| |
| /* |
| * Put the new queue at the front of the of the current list, |
| * so we know that it will be selected next. |
| */ |
| BUG_ON(!cfq_cfqq_on_rr(cfqq)); |
| |
| cfq_service_tree_add(cfqd, cfqq, 1); |
| |
| cfqq->slice_end = 0; |
| cfq_mark_cfqq_slice_new(cfqq); |
| } |
| |
| /* |
| * Called when a new fs request (rq) is added (to cfqq). Check if there's |
| * something we should do about it |
| */ |
| static void |
| cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq, |
| struct request *rq) |
| { |
| struct cfq_io_cq *cic = RQ_CIC(rq); |
| |
| cfqd->rq_queued++; |
| if (rq->cmd_flags & REQ_PRIO) |
| cfqq->prio_pending++; |
| |
| cfq_update_io_thinktime(cfqd, cfqq, cic); |
| cfq_update_io_seektime(cfqd, cfqq, rq); |
| cfq_update_idle_window(cfqd, cfqq, cic); |
| |
| cfqq->last_request_pos = blk_rq_pos(rq) + blk_rq_sectors(rq); |
| |
| if (cfqq == cfqd->active_queue) { |
| /* |
| * Remember that we saw a request from this process, but |
| * don't start queuing just yet. Otherwise we risk seeing lots |
| * of tiny requests, because we disrupt the normal plugging |
| * and merging. If the request is already larger than a single |
| * page, let it rip immediately. For that case we assume that |
| * merging is already done. Ditto for a busy system that |
| * has other work pending, don't risk delaying until the |
| * idle timer unplug to continue working. |
|