From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@kernel.dk>, Tejun Heo <tj@kernel.org>
Cc: Fabio Checconi <fchecconi@gmail.com>,
Arianna Avanzini <avanzini.arianna@gmail.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, linus.walleij@linaro.org,
broonie@kernel.org, Paolo Valente <paolo.valente@linaro.org>
Subject: [PATCH V2 13/16] block, bfq: boost the throughput with random I/O on NCQ-capable HDDs
Date: Fri, 31 Mar 2017 14:47:40 +0200 [thread overview]
Message-ID: <20170331124743.3530-14-paolo.valente@linaro.org> (raw)
In-Reply-To: <20170331124743.3530-1-paolo.valente@linaro.org>
This patch is basically the counterpart, for NCQ-capable rotational
devices, of the previous patch. Exactly as the previous patch does on
flash-based devices and for any workload, this patch disables device
idling on rotational devices, but only for random I/O. In fact, only
with these queues disabling idling boosts the throughput on
NCQ-capable rotational devices. To not break service guarantees,
idling is disabled for NCQ-enabled rotational devices only when the
same symmetry conditions considered in the previous patches hold.
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Arianna Avanzini <avanzini.arianna@gmail.com>
---
block/bfq-iosched.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c
index ca1ae24..738fd5f 100644
--- a/block/bfq-iosched.c
+++ b/block/bfq-iosched.c
@@ -6423,20 +6423,15 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
* The next variable takes into account the cases where idling
* boosts the throughput.
*
- * The value of the variable is computed considering that
- * idling is usually beneficial for the throughput if:
+ * The value of the variable is computed considering, first, that
+ * idling is virtually always beneficial for the throughput if:
* (a) the device is not NCQ-capable, or
* (b) regardless of the presence of NCQ, the device is rotational
- * and the request pattern for bfqq is I/O-bound (possible
- * throughput losses caused by granting idling to seeky queues
- * are mitigated by the fact that, in all scenarios where
- * boosting throughput is the best thing to do, i.e., in all
- * symmetric scenarios, only a minimal idle time is allowed to
- * seeky queues).
+ * and the request pattern for bfqq is I/O-bound and sequential.
*
* Secondly, and in contrast to the above item (b), idling an
* NCQ-capable flash-based device would not boost the
- * throughput even with intense I/O; rather it would lower
+ * throughput even with sequential I/O; rather it would lower
* the throughput in proportion to how fast the device
* is. Accordingly, the next variable is true if any of the
* above conditions (a) and (b) is true, and, in particular,
@@ -6444,7 +6439,8 @@ static bool bfq_bfqq_may_idle(struct bfq_queue *bfqq)
* device.
*/
idling_boosts_thr = !bfqd->hw_tag ||
- (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq));
+ (!blk_queue_nonrot(bfqd->queue) && bfq_bfqq_IO_bound(bfqq) &&
+ bfq_bfqq_idle_window(bfqq));
/*
* The value of the next variable,
--
2.10.0
next prev parent reply other threads:[~2017-03-31 12:50 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-31 12:47 [PATCH V2 00/16] Introduce the BFQ I/O scheduler Paolo Valente
2017-03-31 12:47 ` [PATCH V2 01/16] block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler Paolo Valente
2017-03-31 12:47 ` [PATCH V2 02/16] block, bfq: add full hierarchical scheduling and cgroups support Paolo Valente
2017-03-31 12:47 ` [PATCH V2 03/16] block, bfq: improve throughput boosting Paolo Valente
2017-03-31 12:47 ` [PATCH V2 04/16] block, bfq: modify the peak-rate estimator Paolo Valente
2017-03-31 15:31 ` Bart Van Assche
2017-04-04 10:42 ` Paolo Valente
2017-04-04 15:28 ` Bart Van Assche
2017-04-06 19:37 ` Paolo Valente
2017-03-31 12:47 ` [PATCH V2 05/16] block, bfq: add more fairness with writes and slow processes Paolo Valente
2017-03-31 12:47 ` [PATCH V2 06/16] block, bfq: improve responsiveness Paolo Valente
2017-03-31 12:47 ` [PATCH V2 07/16] block, bfq: reduce I/O latency for soft real-time applications Paolo Valente
2017-03-31 12:47 ` [PATCH V2 08/16] block, bfq: preserve a low latency also with NCQ-capable drives Paolo Valente
2017-03-31 12:47 ` [PATCH V2 09/16] block, bfq: reduce latency during request-pool saturation Paolo Valente
2017-03-31 12:47 ` [PATCH V2 10/16] block, bfq: add Early Queue Merge (EQM) Paolo Valente
2017-03-31 12:47 ` [PATCH V2 11/16] block, bfq: reduce idling only in symmetric scenarios Paolo Valente
2017-03-31 15:20 ` Bart Van Assche
2017-04-07 7:47 ` Paolo Valente
2017-03-31 12:47 ` [PATCH V2 12/16] block, bfq: boost the throughput on NCQ-capable flash-based devices Paolo Valente
2017-03-31 12:47 ` Paolo Valente [this message]
2017-03-31 12:47 ` [PATCH V2 14/16] block, bfq: handle bursts of queue activations Paolo Valente
2017-03-31 12:47 ` [PATCH V2 15/16] block, bfq: remove all get and put of I/O contexts Paolo Valente
2017-03-31 12:47 ` [PATCH V2 16/16] block, bfq: split bfq-iosched.c into multiple source files Paolo Valente
2017-04-02 10:02 ` kbuild test robot
2017-04-11 11:00 ` Paolo Valente
2017-04-12 8:39 ` [kbuild-all] " Ye Xiaolong
2017-04-12 9:24 ` Paolo Valente
2017-04-12 16:05 ` Paolo Valente
2017-04-10 16:56 ` [PATCH V2 00/16] Introduce the BFQ I/O scheduler Bart Van Assche
2017-04-11 8:43 ` Paolo Valente
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