[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 <axboe@suse.de>
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index e2e6ad0..c88f161d 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -123,8 +123,6 @@
*/
struct hlist_head *crq_hash;
- unsigned int max_queued;
-
mempool_t *crq_pool;
int rq_in_driver;
@@ -1910,7 +1908,6 @@
__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 @@
}
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 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 @@
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;