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Date: Tue, 10 Nov 2009 14:54:57 +0100
From: Corrado Zoccolo <czoccolo@...il.com>
To: "Linux-Kernel" <linux-kernel@...r.kernel.org>,
Jens Axboe <jens.axboe@...cle.com>,
Jeff Moyer <jmoyer@...hat.com>
Subject: [RFC, PATCH] cfq-iosched: remove redundant queuing detection code
The core block layer already has code to detect presence of command
queuing devices. We convert cfq to use that instead of re-doing the
computation.
Signed-off-by: Corrado Zoccolo <czoccolo@...il.com>
---
block/cfq-iosched.c | 55 ++------------------------------------------------
1 files changed, 3 insertions(+), 52 deletions(-)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 829d87d..a185742 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -186,14 +186,6 @@ struct cfq_data {
int sync_flight;
/*
- * queue-depth detection
- */
- int rq_queued;
- int hw_tag;
- int hw_tag_samples;
- int rq_in_driver_peak;
-
- /*
* idle window management
*/
struct timer_list idle_slice_timer;
@@ -912,7 +904,6 @@ static void cfq_remove_request(struct request *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--;
@@ -1227,7 +1218,7 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
* 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)
+ if (blk_queue_nonrot(cfqd->queue) && blk_queue_queuing(cfqd->queue))
return;
WARN_ON(!RB_EMPTY_ROOT(&cfqq->sort_list));
@@ -1273,7 +1264,8 @@ static void cfq_arm_slice_timer(struct cfq_data *cfqd)
if (cfqd->serving_type == SYNC_NOIDLE_WORKLOAD &&
service_tree_for(cfqd->serving_prio, SYNC_NOIDLE_WORKLOAD, cfqd)
->count > 0) {
- if (blk_queue_nonrot(cfqd->queue) || cfqd->hw_tag)
+ if (blk_queue_nonrot(cfqd->queue) ||
+ blk_queue_queuing(cfqd->queue))
return;
sl = min(sl, msecs_to_jiffies(CFQ_MIN_TT));
}
@@ -2462,7 +2454,6 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
{
struct cfq_io_context *cic = RQ_CIC(rq);
- cfqd->rq_queued++;
if (rq_is_meta(rq))
cfqq->meta_pending++;
@@ -2518,43 +2509,6 @@ static void cfq_insert_request(struct request_queue *q, struct request *rq)
cfq_rq_enqueued(cfqd, cfqq, rq);
}
-/*
- * Update hw_tag based on peak queue depth over 50 samples under
- * sufficient load.
- */
-static void cfq_update_hw_tag(struct cfq_data *cfqd)
-{
- struct cfq_queue *cfqq = cfqd->active_queue;
-
- if (rq_in_driver(cfqd) > cfqd->rq_in_driver_peak)
- cfqd->rq_in_driver_peak = rq_in_driver(cfqd);
-
- if (cfqd->rq_queued <= CFQ_HW_QUEUE_MIN &&
- rq_in_driver(cfqd) <= CFQ_HW_QUEUE_MIN)
- return;
-
- /*
- * If active queue hasn't enough requests and can idle, cfq might not
- * dispatch sufficient requests to hardware. Don't zero hw_tag in this
- * case
- */
- if (cfqq && cfq_cfqq_idle_window(cfqq) &&
- cfqq->dispatched + cfqq->queued[0] + cfqq->queued[1] <
- CFQ_HW_QUEUE_MIN && rq_in_driver(cfqd) < CFQ_HW_QUEUE_MIN)
- return;
-
- if (cfqd->hw_tag_samples++ < 50)
- return;
-
- if (cfqd->rq_in_driver_peak >= CFQ_HW_QUEUE_MIN)
- cfqd->hw_tag = 1;
- else
- cfqd->hw_tag = 0;
-
- cfqd->hw_tag_samples = 0;
- cfqd->rq_in_driver_peak = 0;
-}
-
static void cfq_completed_request(struct request_queue *q, struct request *rq)
{
struct cfq_queue *cfqq = RQ_CFQQ(rq);
@@ -2565,8 +2519,6 @@ static void cfq_completed_request(struct request_queue *q, struct request *rq)
now = jiffies;
cfq_log_cfqq(cfqd, cfqq, "complete");
- cfq_update_hw_tag(cfqd);
-
WARN_ON(!cfqd->rq_in_driver[sync]);
WARN_ON(!cfqq->dispatched);
cfqd->rq_in_driver[sync]--;
@@ -2959,7 +2911,6 @@ static void *cfq_init_queue(struct request_queue *q)
cfqd->cfq_slice_async_rq = cfq_slice_async_rq;
cfqd->cfq_slice_idle = cfq_slice_idle;
cfqd->cfq_latency = 1;
- cfqd->hw_tag = 1;
cfqd->last_end_sync_rq = jiffies;
return cfqd;
}
--
1.6.2.5
--
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