blob: abc5d8087b0c21708c4dff97ddb5a23c59a8eea2 [file] [log] [blame]
/*
* 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/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-cgroup.h"
/*
* tunables
*/
/* max queue in one round of service */
static const int cfq_quantum = 4;
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 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 8 * 1024
#define CFQQ_SEEKY(cfqq) ((cfqq)->seek_mean > CFQQ_SEEK_THR)
#define RQ_CIC(rq) \
((struct cfq_io_context *) (rq)->elevator_private)
#define RQ_CFQQ(rq) (struct cfq_queue *) ((rq)->elevator_private2)
static struct kmem_cache *cfq_pool;
static struct kmem_cache *cfq_ioc_pool;
static DEFINE_PER_CPU(unsigned long, cfq_ioc_count);
static struct completion *ioc_gone;
static DEFINE_SPINLOCK(ioc_gone_lock);
#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)
/*
* 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;
u64 min_vdisktime;
struct rb_node *active;
unsigned total_weight;
};
#define CFQ_RB_ROOT (struct cfq_rb_root) { RB_ROOT, NULL, 0, 0, }
/*
* Per process-grouping structure
*/
struct cfq_queue {
/* reference count */
atomic_t 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;
/* time when first request from queue completed and slice started. */
unsigned long slice_start;
unsigned long slice_end;
long slice_resid;
unsigned int slice_dispatch;
/* pending metadata requests */
int meta_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, org_ioprio_class;
unsigned int seek_samples;
u64 seek_total;
sector_t seek_mean;
sector_t last_request_pos;
pid_t pid;
struct cfq_rb_root *service_tree;
struct cfq_queue *new_cfqq;
struct cfq_group *cfqg;
struct cfq_group *orig_cfqg;
/* Sectors dispatched in current 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,
};
/*
* 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;
bool on_st;
/* number of cfqq currently on this group */
int nr_cfqq;
/* Per group busy queus average. Useful for workload slice calc. */
unsigned int busy_queues_avg[2];
/*
* rr lists of queues with requests, onle rr for each priority class.
* 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;
atomic_t ref;
#endif
};
/*
* 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;
bool noidle_tree_requires_idle;
/*
* 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;
int rq_in_driver[2];
int sync_flight;
/*
* 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_context *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_latency;
unsigned int cfq_group_isolation;
struct list_head cic_list;
/*
* 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;
struct rcu_head rcu;
};
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_DEBUG_CFQ_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 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 struct cfq_io_context *cfq_cic_lookup(struct cfq_data *,
struct io_context *);
static inline int rq_in_driver(struct cfq_data *cfqd)
{
return cfqd->rq_in_driver[0] + cfqd->rq_in_driver[1];
}
static inline struct cfq_queue *cic_to_cfqq(struct cfq_io_context *cic,
bool is_sync)
{
return cic->cfqq[is_sync];
}
static inline void cic_set_cfqq(struct cfq_io_context *cic,
struct cfq_queue *cfqq, bool is_sync)
{
cic->cfqq[is_sync] = cfqq;
}
/*
* 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_rw_flagged(bio, BIO_RW_SYNCIO);
}
/*
* 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);
}
}
static int cfq_queue_empty(struct request_queue *q)
{
struct cfq_data *cfqd = q->elevator->elevator_data;
return !cfqd->rq_queued;
}
/*
* 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)
{
u64 vdisktime = st->min_vdisktime;
struct cfq_group *cfqg;
if (st->active) {
cfqg = rb_entry_cfqg(st->active);
vdisktime = cfqg->vdisktime;
}
if (st->left) {
cfqg = rb_entry_cfqg(st->left);
vdisktime = min_vdisktime(vdisktime, cfqg->vdisktime);
}
st->min_vdisktime = max_vdisktime(st->min_vdisktime, 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 void
cfq_set_prio_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);
}
}
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 0;
if (time_before(jiffies, cfqq->slice_end))
return 0;
return 1;
}
/*
* 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 rq1;
else if (rq_is_sync(rq2) && !rq_is_sync(rq1))
return rq2;
if (rq_is_meta(rq1) && !rq_is_meta(rq2))
return rq1;
else if (rq_is_meta(rq2) && !rq_is_meta(rq1))
return 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_group_service_tree_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 (cfqg->on_st)
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 continously 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);
cfqg->on_st = true;
st->total_weight += cfqg->weight;
}
static void
cfq_group_service_tree_del(struct cfq_data *cfqd, struct cfq_group *cfqg)
{
struct cfq_rb_root *st = &cfqd->grp_service_tree;
if (st->active == &cfqg->rb_node)
st->active = NULL;
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");
cfqg->on_st = false;
st->total_weight -= cfqg->weight;
if (!RB_EMPTY_NODE(&cfqg->rb_node))
cfq_rb_erase(&cfqg->rb_node, st);
cfqg->saved_workload_slice = 0;
blkiocg_update_blkio_group_dequeue_stats(&cfqg->blkg, 1);
}
static inline unsigned int cfq_cfqq_slice_usage(struct cfq_queue *cfqq)
{
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)
slice_used = cfqq->allocated_slice;
}
cfq_log_cfqq(cfqq->cfqd, cfqq, "sl_used=%u sect=%lu", slice_used,
cfqq->nr_sectors);
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_sl;
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_sl = cfq_cfqq_slice_usage(cfqq);
if (!cfq_cfqq_sync(cfqq) && !nr_sync)
charge_sl = cfqq->allocated_slice;
/* Can't update vdisktime while group is on service tree */
cfq_rb_erase(&cfqg->rb_node, st);
cfqg->vdisktime += cfq_scale_slice(charge_sl, cfqg);
__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);
blkiocg_update_blkio_group_stats(&cfqg->blkg, used_sl,
cfqq->nr_sectors);
}
#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;
}
void
cfq_update_blkio_group_weight(struct blkio_group *blkg, unsigned int weight)
{
cfqg_of_blkg(blkg)->weight = weight;
}
static struct cfq_group *
cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create)
{
struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup);
struct cfq_group *cfqg = NULL;
void *key = cfqd;
int i, j;
struct cfq_rb_root *st;
struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info;
unsigned int major, minor;
/* Do we need to take this reference */
if (!blkiocg_css_tryget(blkcg))
return NULL;;
cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key));
if (cfqg || !create)
goto done;
cfqg = kzalloc_node(sizeof(*cfqg), GFP_ATOMIC, cfqd->queue->node);
if (!cfqg)
goto done;
cfqg->weight = blkcg->weight;
for_each_cfqg_st(cfqg, i, j, st)
*st = CFQ_RB_ROOT;
RB_CLEAR_NODE(&cfqg->rb_node);
/*
* 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.
*/
atomic_set(&cfqg->ref, 1);
/* Add group onto cgroup list */
sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor);
blkiocg_add_blkio_group(blkcg, &cfqg->blkg, (void *)cfqd,
MKDEV(major, minor));
/* Add group on cfqd list */
hlist_add_head(&cfqg->cfqd_node, &cfqd->cfqg_list);
done:
blkiocg_css_put(blkcg);
return cfqg;
}
/*
* Search for the cfq group current task belongs to. If create = 1, then also
* create the cfq group if it does not exist. request_queue lock must be held.
*/
static struct cfq_group *cfq_get_cfqg(struct cfq_data *cfqd, int create)
{
struct cgroup *cgroup;
struct cfq_group *cfqg = NULL;
rcu_read_lock();
cgroup = task_cgroup(current, blkio_subsys_id);
cfqg = cfq_find_alloc_cfqg(cfqd, cgroup, create);
if (!cfqg && create)
cfqg = &cfqd->root_group;
rcu_read_unlock();
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 */
atomic_inc(&cfqq->cfqg->ref);
}
static void cfq_put_cfqg(struct cfq_group *cfqg)
{
struct cfq_rb_root *st;
int i, j;
BUG_ON(atomic_read(&cfqg->ref) <= 0);
if (!atomic_dec_and_test(&cfqg->ref))
return;
for_each_cfqg_st(cfqg, i, j, st)
BUG_ON(!RB_EMPTY_ROOT(&st->rb) || st->active != NULL);
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);
/*
* 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 (!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.
*/
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, int create)
{
return &cfqd->root_group;
}
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;
int group_changed = 0;
#ifdef CONFIG_CFQ_GROUP_IOSCHED
if (!cfqd->cfq_group_isolation
&& cfqq_type(cfqq) == SYNC_NOIDLE_WORKLOAD
&& cfqq->cfqg && cfqq->cfqg != &cfqd->root_group) {
/* Move this cfq to root group */
cfq_log_cfqq(cfqd, cfqq, "moving to root group");
if (!RB_EMPTY_NODE(&cfqq->rb_node))
cfq_group_service_tree_del(cfqd, cfqq->cfqg);
cfqq->orig_cfqg = cfqq->cfqg;
cfqq->cfqg = &cfqd->root_group;
atomic_inc(&cfqd->root_group.ref);
group_changed = 1;
} else if (!cfqd->cfq_group_isolation
&& cfqq_type(cfqq) == SYNC_WORKLOAD && cfqq->orig_cfqg) {
/* cfqq is sequential now needs to go to its original group */
BUG_ON(cfqq->cfqg != &cfqd->root_group);
if (!RB_EMPTY_NODE(&cfqq->rb_node))
cfq_group_service_tree_del(cfqd, cfqq->cfqg);
cfq_put_cfqg(cfqq->cfqg);
cfqq->cfqg = cfqq->orig_cfqg;
cfqq->orig_cfqg = NULL;
group_changed = 1;
cfq_log_cfqq(cfqd, cfqq, "moved to origin group");
}
#endif
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) && !group_changed)
return;
cfq_group_service_tree_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++;
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_service_tree_del(cfqd, cfqq->cfqg);
BUG_ON(!cfqd->busy_queues);
cfqd->busy_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 *__alias, *prev;
cfqq->queued[rq_is_sync(rq)]++;
/*
* looks a little odd, but the first insert might return an alias.
* if that happens, put the alias on the dispatch list
*/
while ((__alias = elv_rb_add(&cfqq->sort_list, rq)) != NULL)
cfq_dispatch_insert(cfqd->queue, __alias);
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_add_rq_rb(rq);
}
static struct request *
cfq_find_rq_fmerge(struct cfq_data *cfqd, struct bio *bio)
{
struct task_struct *tsk = current;
struct cfq_io_context *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[rq_is_sync(rq)]++;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "activate rq, drv=%d",
rq_in_driver(cfqd));
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;
const int sync = rq_is_sync(rq);
WARN_ON(!cfqd->rq_in_driver[sync]);
cfqd->rq_in_driver[sync]--;
cfq_log_cfqq(cfqd, RQ_CFQQ(rq), "deactivate rq, drv=%d",
rq_in_driver(cfqd));
}
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--;
if (rq_is_meta(rq)) {
WARN_ON(!cfqq->meta_pending);
cfqq->meta_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_merged_requests(struct request_queue *q, struct request *rq,
struct request *next)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
/*
* 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);
}
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_context *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. Allow
* merge only if rq is queued there.
*/
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 void __cfq_set_active_queue(struct cfq_data *cfqd,
struct cfq_queue *cfqq)
{
if (cfqq) {
cfq_log_cfqq(cfqd, cfqq, "set_active");
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);
del_timer(&cfqd->idle_slice_timer);
}
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))
del_timer(&cfqd->idle_slice_timer);
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 && !cfq_cfqq_slice_new(cfqq)) {
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 (&cfqq->cfqg->rb_node == cfqd->grp_service_tree.active)
cfqd->grp_service_tree.active = NULL;
if (cfqd->active_cic) {
put_io_context(cfqd->active_cic->ioc);
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, bool for_preempt)
{
sector_t sdist = cfqq->seek_mean;
if (!sample_valid(cfqq->seek_samples))
sdist = CFQQ_SEEK_THR;
/* if seek_mean is big, using it as close criteria is meaningless */
if (sdist > CFQQ_SEEK_THR && !for_preempt)
sdist = CFQQ_SEEK_THR;
return cfq_dist_from_last(cfqd, rq) <= sdist;
}
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, false))
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, false))
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_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);
/* 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.
*/
return service_tree->count == 1 && cfq_cfqq_sync(cfqq);
}
static void cfq_arm_slice_timer(struct cfq_data *cfqd)
{
struct cfq_queue *cfqq = cfqd->active_queue;
struct cfq_io_context *cic;
unsigned long sl;
/*
* 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 (!cfqd->cfq_slice_idle || !cfq_should_idle(cfqd, cfqq))
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->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_samples) &&
(cfqq->slice_end - jiffies < cic->ttime_mean))
return;
cfq_mark_cfqq_wait_request(cfqq);
sl = cfqd->cfq_slice_idle;
mod_timer(&cfqd->idle_slice_timer, jiffies + sl);
cfq_log_cfqq(cfqd, cfqq, "arm_idle: %lu", sl);
}
/*
* 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++;
elv_dispatch_sort(q, rq);
if (cfq_cfqq_sync(cfqq))
cfqd->sync_flight++;
cfqq->nr_sectors += blk_rq_sectors(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 + base_rq * (CFQ_PRIO_LISTS - 1 - 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 = atomic_read(&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;
atomic_add(process_refs, &new_cfqq->ref);
} else {
new_cfqq->new_cfqq = cfqq;
atomic_add(new_process_refs, &cfqq->ref);
}
}
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;
if (!cfqg) {
cfqd->serving_prio = IDLE_WORKLOAD;
cfqd->workload_expires = jiffies + 1;
return;
}
/* 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;
}
/*
* 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;
/* 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);
cfqd->workload_expires = jiffies + slice;
cfqd->noidle_tree_requires_idle = false;
}
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);
st->active = &cfqg->rb_node;
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 expire;
}
/*
* 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->dispatched && cfq_should_idle(cfqd, cfqq))) {
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;
while ((cfqq = cfq_get_next_queue_forced(cfqd)) != NULL)
dispatched += __cfq_forced_dispatch_cfqq(cfqq);
cfq_slice_expired(cfqd, 0);
BUG_ON(cfqd->busy_queues);
cfq_log(cfqd, "forced_dispatch=%d", dispatched);
return dispatched;
}
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_driver[BLK_RW_ASYNC])
return false;
/*
* If this is an async queue and we have sync IO in flight, let it wait
*/
if (cfqd->sync_flight && !cfq_cfqq_sync(cfqq))
return false;
max_dispatch = cfqd->cfq_quantum;
if (cfq_class_idle(cfqq))
max_dispatch = 1;
/*
* Does this cfqq already have too much IO in flight?
*/
if (cfqq->dispatched >= max_dispatch) {
/*
* idle queue must always only have a single IO in flight
*/
if (cfq_class_idle(cfqq))
return false;
/*
* We have other queues, don't allow more IO from this one
*/
if (cfqd->busy_queues > 1)
return false;
/*
* Sole queue user, no limit
*/
max_dispatch = -1;
}
/*
* 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_context *cic = RQ_CIC(rq);
atomic_long_inc(&cic->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, *orig_cfqg;
BUG_ON(atomic_read(&cfqq->ref) <= 0);
if (!atomic_dec_and_test(&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;
orig_cfqg = cfqq->orig_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);
if (orig_cfqg)
cfq_put_cfqg(orig_cfqg);
}
/*
* Must always be called with the rcu_read_lock() held
*/
static void
__call_for_each_cic(struct io_context *ioc,
void (*func)(struct io_context *, struct cfq_io_context *))
{
struct cfq_io_context *cic;
struct hlist_node *n;
hlist_for_each_entry_rcu(cic, n, &ioc->cic_list, cic_list)
func(ioc, cic);
}
/*
* Call func for each cic attached to this ioc.
*/
static void
call_for_each_cic(struct io_context *ioc,
void (*func)(struct io_context *, struct cfq_io_context *))
{
rcu_read_lock();
__call_for_each_cic(ioc, func);
rcu_read_unlock();
}
static void cfq_cic_free_rcu(struct rcu_head *head)
{
struct cfq_io_context *cic;
cic = container_of(head, struct cfq_io_context, rcu_head);
kmem_cache_free(cfq_ioc_pool, cic);
elv_ioc_count_dec(cfq_ioc_count);
if (ioc_gone) {
/*
* CFQ scheduler is exiting, grab exit lock and check
* the pending io context count. If it hits zero,
* complete ioc_gone and set it back to NULL
*/
spin_lock(&ioc_gone_lock);
if (ioc_gone && !elv_ioc_count_read(cfq_ioc_count)) {
complete(ioc_gone);
ioc_gone = NULL;
}
spin_unlock(&ioc_gone_lock);
}
}
static void cfq_cic_free(struct cfq_io_context *cic)
{
call_rcu(&cic->rcu_head, cfq_cic_free_rcu);
}
static void cic_free_func(struct io_context *ioc, struct cfq_io_context *cic)
{
unsigned long flags;
BUG_ON(!cic->dead_key);
spin_lock_irqsave(&ioc->lock, flags);
radix_tree_delete(&ioc->radix_root, cic->dead_key);
hlist_del_rcu(&cic->cic_list);
spin_unlock_irqrestore(&ioc->lock, flags);
cfq_cic_free(cic);
}
/*
* Must be called with rcu_read_lock() held or preemption otherwise disabled.
* Only two callers of this - ->dtor() which is called with the rcu_read_lock(),
* and ->trim() which is called with the task lock held
*/
static void cfq_free_io_context(struct io_context *ioc)
{
/*
* ioc->refcount is zero here, or we are called from elv_unregister(),
* so no more cic's are allowed to be linked into this ioc. So it
* should be ok to iterate over the known list, we will see all cic's
* since no new ones are added.
*/
__call_for_each_cic(ioc, cic_free_func);
}
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_exit_single_io_context(struct cfq_data *cfqd,
struct cfq_io_context *cic)
{
struct io_context *ioc = cic->ioc;
list_del_init(&cic->queue_list);
/*
* Make sure key == NULL is seen for dead queues
*/
smp_wmb();
cic->dead_key = (unsigned long) cic->key;
cic->key = NULL;
if (ioc->ioc_data == cic)
rcu_assign_pointer(ioc->ioc_data, NULL);
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_exit_single_io_context(struct io_context *ioc,
struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
if (cfqd) {
struct request_queue *q = cfqd->queue;
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
/*
* Ensure we get a fresh copy of the ->key to prevent
* race between exiting task and queue
*/
smp_read_barrier_depends();
if (cic->key)
__cfq_exit_single_io_context(cfqd, cic);
spin_unlock_irqrestore(q->queue_lock, flags);
}
}
/*
* The process that ioc belongs to has exited, we need to clean up
* and put the internal structures we have that belongs to that process.
*/
static void cfq_exit_io_context(struct io_context *ioc)
{
call_for_each_cic(ioc, cfq_exit_single_io_context);
}
static struct cfq_io_context *
cfq_alloc_io_context(struct cfq_data *cfqd, gfp_t gfp_mask)
{
struct cfq_io_context *cic;
cic = kmem_cache_alloc_node(cfq_ioc_pool, gfp_mask | __GFP_ZERO,
cfqd->queue->node);
if (cic) {
cic->last_end_request = jiffies;
INIT_LIST_HEAD(&cic->queue_list);
INIT_HLIST_NODE(&cic->cic_list);
cic->dtor = cfq_free_io_context;
cic->exit = cfq_exit_io_context;
elv_ioc_count_inc(cfq_ioc_count);
}
return cic;
}
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;
cfqq->org_ioprio_class = cfqq->ioprio_class;
cfq_clear_cfqq_prio_changed(cfqq);
}
static void changed_ioprio(struct io_context *ioc, struct cfq_io_context *cic)
{
struct cfq_data *cfqd = cic->key;
struct cfq_queue *cfqq;
unsigned long flags;
if (unlikely(!cfqd))
return;
spin_lock_irqsave(cfqd->queue->queue_lock, flags);
cfqq = cic->cfqq[BLK_RW_ASYNC];
if (cfqq) {
struct cfq_queue *new_cfqq;
new_cfqq = cfq_get_queue(cfqd, BLK_RW_ASYNC, cic->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);
spin_unlock_irqrestore(cfqd->queue->queue_lock, flags);
}
static void cfq_ioc_set_ioprio(struct io_context *ioc)
{
call_for_each_cic(ioc, changed_ioprio);
ioc->ioprio_changed = 0;
}
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);
atomic_set(&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 io_context *ioc, struct cfq_io_context *cic)
{
struct cfq_queue *sync_cfqq = cic_to_cfqq(cic, 1);
struct cfq_data *cfqd = cic->key;
unsigned long flags;
struct request_queue *q;
if (unlikely(!cfqd))
return;
q = cfqd->queue;
spin_lock_irqsave(q->queue_lock, flags);
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);
}
spin_unlock_irqrestore(q->queue_lock, flags);
}
static void cfq_ioc_set_cgroup(struct io_context *ioc)
{
call_for_each_cic(ioc, changed_cgroup);
ioc->cgroup_changed = 0;
}
#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_context *cic;
struct cfq_group *cfqg;
retry:
cfqg = cfq_get_cfqg(cfqd, 1);
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)) {
atomic_inc(&cfqq->ref);
*async_cfqq = cfqq;
}
atomic_inc(&cfqq->ref);
return cfqq;
}
/*
* We drop cfq io contexts lazily, so we may find a dead one.
*/
static void
cfq_drop_dead_cic(struct cfq_data *cfqd, struct io_context *ioc,
struct cfq_io_context *cic)
{
unsigned long flags;
WARN_ON(!list_empty(&cic->queue_list));
spin_lock_irqsave(&ioc->lock, flags);
BUG_ON(