Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1451400

[PATCH RFC V8 02/22] block, cfq: remove close-based preemption

Show all headers | View raw

From: Arianna Avanzini <avanzini.arianna@gmail.com>

CFQ may preempt the queue currently in service if a new request, for a
different queue, happens to be close to the last-dispatched
request. This boosts the throughput with processes that issue close
requests, but whose I/O patterns are not regularly interleaved enough
to trigger the activation of the queue-merging heuristic removed in
the previous commit. BFQ does not need to perform any such preemption,
because the queue-merging mechanism of BFQ (EQM) is reactive enough to
merge queues also in the presence of irregularly interleaved I/O.

Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
---
 block/cfq-iosched.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 18a7291..1b9fa10 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -2677,12 +2677,6 @@ static inline sector_t cfq_dist_from_last(struct cfq_data *cfqd,
 		return cfqd->last_position - blk_rq_pos(rq);
 }
 
-static inline int cfq_rq_close(struct cfq_data *cfqd, struct cfq_queue *cfqq,
-			       struct request *rq)
-{
-	return cfq_dist_from_last(cfqd, rq) <= CFQQ_CLOSE_THR;
-}
-
 /*
  * Determine whether we should enforce idle window for this queue.
  */
@@ -3724,13 +3718,6 @@ cfq_should_preempt(struct cfq_data *cfqd, struct cfq_queue *new_cfqq,
 	if (!cfqd->active_cic || !cfq_cfqq_wait_request(cfqq))
 		return false;
 
-	/*
-	 * if this request is as-good as one we would expect from the
-	 * current cfqq, let it preempt
-	 */
-	if (cfq_rq_close(cfqd, cfqq, rq))
-		return true;
-
 	return false;
 }
 
-- 
1.9.1

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH RFC V8 00/22] Replace the CFQ I/O Scheduler with BFQ Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 12/22] block, bfq: modify the peak-rate estimator Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 04/22] block, cfq: remove SSD-related logic Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 17/22] block, bfq: reduce latency during request-pool saturation Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 13/22] block, bfq: add more fairness with writes and slow processes Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 08/22] block, cfq: get rid of latency tunables Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 20/22] block, bfq: boost the throughput on NCQ-capable flash-based devices Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 19/22] block, bfq: reduce idling only in symmetric scenarios Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 22/22] block, bfq: handle bursts of queue activations Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 16/22] block, bfq: preserve a low latency also with NCQ-capable drives Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 11/22] block, bfq: improve throughput boosting Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 15/22] block, bfq: reduce I/O latency for soft real-time applications Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 02/22] block, cfq: remove close-based preemption Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 21/22] block, bfq: boost the throughput with random I/O on NCQ-capable HDDs Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 18/22] block, bfq: add Early Queue Merge (EQM) Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  [PATCH RFC V8 07/22] block, cfq: get rid of workload type Paolo Valente <paolo.valente@linaro.org> - 2016-07-27 18:20 +0200
  Re: [PATCH RFC V8 00/22] Replace the CFQ I/O Scheduler with BFQ Paolo <paolo.valente@linaro.org> - 2016-07-28 19:00 +0200

csiph-web