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authorJens Axboe <axboe@suse.de>2006-06-01 10:12:26 +0200
committerJens Axboe <axboe@suse.de>2006-06-01 10:12:26 +0200
commit25776e3594f841b7fae7b33ebecf009a0a55bed1 (patch)
tree689dcf37ba781ad627ae01be4fcb6f5414f67c1b
parent[PATCH] cfq-iosched: Detect idle process issuing async request (diff)
downloadlinux-dev-25776e3594f841b7fae7b33ebecf009a0a55bed1.tar.xz
linux-dev-25776e3594f841b7fae7b33ebecf009a0a55bed1.zip
[PATCH] cfq-iosched: Detect hardware queueing
If the hardware is doing real queueing, decide that it's worthless to idle the hardware. It does reasonable simultaneous io in that case anyways, and the idling hurts some work loads. Signed-off-by: Jens Axboe <axboe@suse.de>
-rw-r--r--block/cfq-iosched.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 93ba54605eda..5d2047b93eb5 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -133,6 +133,7 @@ struct cfq_data {
mempool_t *crq_pool;
int rq_in_driver;
+ int hw_tag;
/*
* schedule slice state info
@@ -664,6 +665,15 @@ static void cfq_activate_request(request_queue_t *q, struct request *rq)
struct cfq_data *cfqd = q->elevator->elevator_data;
cfqd->rq_in_driver++;
+
+ /*
+ * If the depth is larger 1, it really could be queueing. But lets
+ * make the mark a little higher - idling could still be good for
+ * low queueing, and a low queueing number could also just indicate
+ * a SCSI mid layer like behaviour where limit+1 is often seen.
+ */
+ if (!cfqd->hw_tag && cfqd->rq_in_driver > 4)
+ cfqd->hw_tag = 1;
}
static void cfq_deactivate_request(request_queue_t *q, struct request *rq)
@@ -1465,7 +1475,8 @@ retry:
* set ->slice_left to allow preemption for a new process
*/
cfqq->slice_left = 2 * cfqd->cfq_slice_idle;
- cfq_mark_cfqq_idle_window(cfqq);
+ if (!cfqd->hw_tag)
+ cfq_mark_cfqq_idle_window(cfqq);
cfq_mark_cfqq_prio_changed(cfqq);
cfq_init_prio_data(cfqq);
}
@@ -1656,7 +1667,7 @@ cfq_update_idle_window(struct cfq_data *cfqd, struct cfq_queue *cfqq,
{
int enable_idle = cfq_cfqq_idle_window(cfqq);
- if (!cic->ioc->task || !cfqd->cfq_slice_idle)
+ if (!cic->ioc->task || !cfqd->cfq_slice_idle || cfqd->hw_tag)
enable_idle = 0;
else if (sample_valid(cic->ttime_samples)) {
if (cic->ttime_mean > cfqd->cfq_slice_idle)