From 271f18f102c789f59644bb6c53a69da1df72b2f4 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Tue, 13 Jun 2006 08:08:38 +0200 Subject: [PATCH] [PATCH] cfq-iosched: Don't set the queue batching limits We cannot update them if the user changes nr_requests, so don't set it in the first place. The gains are pretty questionable as well. The batching loss has been shown to decrease throughput. Signed-off-by: Jens Axboe --- block/cfq-iosched.c | 48 +++------------------------------------------ 1 file changed, 3 insertions(+), 45 deletions(-) diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c index e2e6ad0a15..c88f161d3f 100644 --- a/block/cfq-iosched.c +++ b/block/cfq-iosched.c @@ -123,8 +123,6 @@ struct cfq_data { */ struct hlist_head *crq_hash; - unsigned int max_queued; - mempool_t *crq_pool; int rq_in_driver; @@ -1910,7 +1908,6 @@ static inline int __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, struct task_struct *task, int rw) { -#if 1 if ((cfq_cfqq_wait_request(cfqq) || cfq_cfqq_must_alloc(cfqq)) && !cfq_cfqq_must_alloc_slice(cfqq)) { cfq_mark_cfqq_must_alloc_slice(cfqq); @@ -1918,39 +1915,6 @@ __cfq_may_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq, } return ELV_MQUEUE_MAY; -#else - if (!cfqq || task->flags & PF_MEMALLOC) - return ELV_MQUEUE_MAY; - if (!cfqq->allocated[rw] || cfq_cfqq_must_alloc(cfqq)) { - if (cfq_cfqq_wait_request(cfqq)) - return ELV_MQUEUE_MUST; - - /* - * only allow 1 ELV_MQUEUE_MUST per slice, otherwise we - * can quickly flood the queue with writes from a single task - */ - if (rw == READ || !cfq_cfqq_must_alloc_slice(cfqq)) { - cfq_mark_cfqq_must_alloc_slice(cfqq); - return ELV_MQUEUE_MUST; - } - - return ELV_MQUEUE_MAY; - } - if (cfq_class_idle(cfqq)) - return ELV_MQUEUE_NO; - if (cfqq->allocated[rw] >= cfqd->max_queued) { - struct io_context *ioc = get_io_context(GFP_ATOMIC); - int ret = ELV_MQUEUE_NO; - - if (ioc && ioc->nr_batch_requests) - ret = ELV_MQUEUE_MAY; - - put_io_context(ioc); - return ret; - } - - return ELV_MQUEUE_MAY; -#endif } static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) @@ -1979,16 +1943,13 @@ static int cfq_may_queue(request_queue_t *q, int rw, struct bio *bio) static void cfq_check_waiters(request_queue_t *q, struct cfq_queue *cfqq) { struct cfq_data *cfqd = q->elevator->elevator_data; - struct request_list *rl = &q->rq; - if (cfqq->allocated[READ] <= cfqd->max_queued || cfqd->rq_starved) { + if (unlikely(cfqd->rq_starved)) { + struct request_list *rl = &q->rq; + smp_mb(); if (waitqueue_active(&rl->wait[READ])) wake_up(&rl->wait[READ]); - } - - if (cfqq->allocated[WRITE] <= cfqd->max_queued || cfqd->rq_starved) { - smp_mb(); if (waitqueue_active(&rl->wait[WRITE])) wake_up(&rl->wait[WRITE]); } @@ -2278,9 +2239,6 @@ static void *cfq_init_queue(request_queue_t *q, elevator_t *e) cfqd->queue = q; - cfqd->max_queued = q->nr_requests / 4; - q->nr_batching = cfq_queued; - init_timer(&cfqd->idle_slice_timer); cfqd->idle_slice_timer.function = cfq_idle_slice_timer; cfqd->idle_slice_timer.data = (unsigned long) cfqd; -- 2.39.5