From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>,
linux-block@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>
Cc: Bart Van Assche <bart.vanassche@sandisk.com>,
Laurence Oberman <loberman@redhat.com>,
Paolo Valente <paolo.valente@linaro.org>,
Oleksandr Natalenko <oleksandr@natalenko.name>,
Tom Nguyen <tom81094@gmail.com>,
linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org,
Omar Sandoval <osandov@fb.com>,
John Garry <john.garry@huawei.com>
Subject: Re: [PATCH V10 0/8] blk-mq-sched: improve sequential I/O performance
Date: Sat, 14 Oct 2017 09:39:21 -0600 [thread overview]
Message-ID: <1c643ef1-26d8-3fa4-2b65-7e299e6a5ceb@kernel.dk> (raw)
In-Reply-To: <20171014092232.13943-1-ming.lei@redhat.com>
On 10/14/2017 03:22 AM, Ming Lei wrote:
> Hi Jens,
>
> In Red Hat internal storage test wrt. blk-mq scheduler, we found that I/O
> performance is much bad with mq-deadline, especially about sequential I/O
> on some multi-queue SCSI devcies(lpfc, qla2xxx, SRP...)
>
> Turns out one big issue causes the performance regression: requests are
> still dequeued from sw queue/scheduler queue even when ldd's queue is
> busy, so I/O merge becomes quite difficult to make, then sequential IO
> performance degrades a lot.
>
> This issue becomes one of mains reasons for reverting default SCSI_MQ
> in V4.13.
>
> This 8 patches improve this situation, and brings back performance loss.
>
> With this change, SCSI-MQ sequential I/O performance is improved much, Paolo
> reported that mq-deadline performance improved much[2] in his dbench test
> wrt V2. Also performance improvement on lpfc/qla2xx was observed with V1.[1]
Looks good to me, and the kyber fix looks obviously correct to me. I have
applied this series for 4.15. Thanks Ming.
--
Jens Axboe
next prev parent reply other threads:[~2017-10-14 15:39 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-14 9:22 Ming Lei
2017-10-14 9:22 ` [PATCH V10 1/8] blk-mq-sched: dispatch from scheduler only after progress is made on ->dispatch Ming Lei
2017-10-14 9:22 ` [PATCH V10 2/8] blk-mq-sched: move actual dispatching into one helper Ming Lei
2017-10-14 9:22 ` [PATCH V10 3/8] sbitmap: introduce __sbitmap_for_each_set() Ming Lei
2017-10-14 9:22 ` [PATCH V10 4/8] block: kyber: check if there is request in ctx in kyber_has_work() Ming Lei
2017-10-14 9:22 ` [PATCH V10 5/8] blk-mq: introduce .get_budget and .put_budget in blk_mq_ops Ming Lei
2017-10-14 9:22 ` [PATCH V10 6/8] blk-mq-sched: improve dispatching from sw queue Ming Lei
2017-10-14 9:22 ` [PATCH V10 7/8] SCSI: allow to pass null rq to scsi_prep_state_check() Ming Lei
2017-10-14 9:22 ` [PATCH V10 8/8] SCSI: implement .get_budget and .put_budget for blk-mq Ming Lei
2017-10-14 15:39 ` Jens Axboe [this message]
2017-10-14 23:17 ` [PATCH V10 0/8] blk-mq-sched: improve sequential I/O performance Ming Lei
2017-10-14 17:38 ` Oleksandr Natalenko
2017-10-14 23:16 ` Ming Lei
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