| #include "blk-rq-qos.h" |
| |
| /* |
| * Increment 'v', if 'v' is below 'below'. Returns true if we succeeded, |
| * false if 'v' + 1 would be bigger than 'below'. |
| */ |
| static bool atomic_inc_below(atomic_t *v, unsigned int below) |
| { |
| unsigned int cur = atomic_read(v); |
| |
| for (;;) { |
| unsigned int old; |
| |
| if (cur >= below) |
| return false; |
| old = atomic_cmpxchg(v, cur, cur + 1); |
| if (old == cur) |
| break; |
| cur = old; |
| } |
| |
| return true; |
| } |
| |
| bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit) |
| { |
| return atomic_inc_below(&rq_wait->inflight, limit); |
| } |
| |
| void rq_qos_cleanup(struct request_queue *q, struct bio *bio) |
| { |
| struct rq_qos *rqos; |
| |
| for (rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->cleanup) |
| rqos->ops->cleanup(rqos, bio); |
| } |
| } |
| |
| void rq_qos_done(struct request_queue *q, struct request *rq) |
| { |
| struct rq_qos *rqos; |
| |
| for (rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->done) |
| rqos->ops->done(rqos, rq); |
| } |
| } |
| |
| void rq_qos_issue(struct request_queue *q, struct request *rq) |
| { |
| struct rq_qos *rqos; |
| |
| for(rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->issue) |
| rqos->ops->issue(rqos, rq); |
| } |
| } |
| |
| void rq_qos_requeue(struct request_queue *q, struct request *rq) |
| { |
| struct rq_qos *rqos; |
| |
| for(rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->requeue) |
| rqos->ops->requeue(rqos, rq); |
| } |
| } |
| |
| void rq_qos_throttle(struct request_queue *q, struct bio *bio, |
| spinlock_t *lock) |
| { |
| struct rq_qos *rqos; |
| |
| for(rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->throttle) |
| rqos->ops->throttle(rqos, bio, lock); |
| } |
| } |
| |
| void rq_qos_track(struct request_queue *q, struct request *rq, struct bio *bio) |
| { |
| struct rq_qos *rqos; |
| |
| for(rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->track) |
| rqos->ops->track(rqos, rq, bio); |
| } |
| } |
| |
| void rq_qos_done_bio(struct request_queue *q, struct bio *bio) |
| { |
| struct rq_qos *rqos; |
| |
| for(rqos = q->rq_qos; rqos; rqos = rqos->next) { |
| if (rqos->ops->done_bio) |
| rqos->ops->done_bio(rqos, bio); |
| } |
| } |
| |
| /* |
| * Return true, if we can't increase the depth further by scaling |
| */ |
| bool rq_depth_calc_max_depth(struct rq_depth *rqd) |
| { |
| unsigned int depth; |
| bool ret = false; |
| |
| /* |
| * For QD=1 devices, this is a special case. It's important for those |
| * to have one request ready when one completes, so force a depth of |
| * 2 for those devices. On the backend, it'll be a depth of 1 anyway, |
| * since the device can't have more than that in flight. If we're |
| * scaling down, then keep a setting of 1/1/1. |
| */ |
| if (rqd->queue_depth == 1) { |
| if (rqd->scale_step > 0) |
| rqd->max_depth = 1; |
| else { |
| rqd->max_depth = 2; |
| ret = true; |
| } |
| } else { |
| /* |
| * scale_step == 0 is our default state. If we have suffered |
| * latency spikes, step will be > 0, and we shrink the |
| * allowed write depths. If step is < 0, we're only doing |
| * writes, and we allow a temporarily higher depth to |
| * increase performance. |
| */ |
| depth = min_t(unsigned int, rqd->default_depth, |
| rqd->queue_depth); |
| if (rqd->scale_step > 0) |
| depth = 1 + ((depth - 1) >> min(31, rqd->scale_step)); |
| else if (rqd->scale_step < 0) { |
| unsigned int maxd = 3 * rqd->queue_depth / 4; |
| |
| depth = 1 + ((depth - 1) << -rqd->scale_step); |
| if (depth > maxd) { |
| depth = maxd; |
| ret = true; |
| } |
| } |
| |
| rqd->max_depth = depth; |
| } |
| |
| return ret; |
| } |
| |
| void rq_depth_scale_up(struct rq_depth *rqd) |
| { |
| /* |
| * Hit max in previous round, stop here |
| */ |
| if (rqd->scaled_max) |
| return; |
| |
| rqd->scale_step--; |
| |
| rqd->scaled_max = rq_depth_calc_max_depth(rqd); |
| } |
| |
| /* |
| * Scale rwb down. If 'hard_throttle' is set, do it quicker, since we |
| * had a latency violation. |
| */ |
| void rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle) |
| { |
| /* |
| * Stop scaling down when we've hit the limit. This also prevents |
| * ->scale_step from going to crazy values, if the device can't |
| * keep up. |
| */ |
| if (rqd->max_depth == 1) |
| return; |
| |
| if (rqd->scale_step < 0 && hard_throttle) |
| rqd->scale_step = 0; |
| else |
| rqd->scale_step++; |
| |
| rqd->scaled_max = false; |
| rq_depth_calc_max_depth(rqd); |
| } |
| |
| void rq_qos_exit(struct request_queue *q) |
| { |
| while (q->rq_qos) { |
| struct rq_qos *rqos = q->rq_qos; |
| q->rq_qos = rqos->next; |
| rqos->ops->exit(rqos); |
| } |
| } |