From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org,
Linux-Kernal <linux-kernel@vger.kernel.org>,
osandov@fb.com
Subject: Re: [PATCH 7/8] mq-deadline: add blk-mq adaptation of the deadline IO scheduler
Date: Fri, 20 Jan 2017 12:07:03 +0100 [thread overview]
Message-ID: <8191D993-76A7-47F9-AF5D-585B0EA1718B@linaro.org> (raw)
In-Reply-To: <048a5a0a-1793-4698-4bc0-213d36fad161@fb.com>
> Il giorno 17 gen 2017, alle ore 03:47, Jens Axboe <axboe@fb.com> ha scritto:
>
> On 12/22/2016 09:49 AM, Paolo Valente wrote:
>>
>>> Il giorno 17 dic 2016, alle ore 01:12, Jens Axboe <axboe@fb.com> ha scritto:
>>>
>>> This is basically identical to deadline-iosched, except it registers
>>> as a MQ capable scheduler. This is still a single queue design.
>>>
>>
>> One last question (for today ...):in mq-deadline there are no
>> "schedule dispatch" or "unplug work" functions. In blk, CFQ and BFQ
>> do these schedules/unplugs in a lot of cases. What's the right
>> replacement? Just doing nothing?
>
> You just use blk_mq_run_hw_queue() or variants thereof to kick off queue
> runs.
>
Hi Jens,
I'm working on this right now. I have a pair of quick questions about
performance.
In the blk version of bfq, if the in-service bfq_queue happen to have
no more budget when the bfq dispatch function is invoked, then bfq:
returns no request (NULL), immediately expires the in-service
bfq_queue, and schedules a new dispatch. The third step is taken so
that, if other bfq_queues have requests, then a new in-service
bfq_queue will be selected on the upcoming new dispatch, and a new
request will be provided right away.
My questions are: is this dispatch-schedule step still needed with
blk-mq, to avoid a stall? If it is not needed to avoid a stall, would
it still be needed to boost throughput, because it would force an
immediate, next dispatch?
BTW, bfq-mq survived its first request completion. I will provide you
with a link to a github branch as soon as bfq-mq seems able to stand
up with a minimal workload.
Thanks,
Paolo
> --
> Jens Axboe
>
next prev parent reply other threads:[~2017-01-20 11:07 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-17 0:12 [PATCHSET v4] blk-mq-scheduling framework Jens Axboe
2016-12-17 0:12 ` [PATCH 1/8] block: move existing elevator ops to union Jens Axboe
2016-12-17 0:12 ` [PATCH 2/8] blk-mq: make mq_ops a const pointer Jens Axboe
2016-12-17 0:12 ` [PATCH 3/8] block: move rq_ioc() to blk.h Jens Axboe
2016-12-20 10:12 ` Paolo Valente
2016-12-20 15:46 ` Jens Axboe
2016-12-20 22:14 ` Jens Axboe
2016-12-17 0:12 ` [PATCH 4/8] blk-mq: un-export blk_mq_free_hctx_request() Jens Axboe
2016-12-17 0:12 ` [PATCH 5/8] blk-mq: export some helpers we need to the scheduling framework Jens Axboe
2016-12-17 0:12 ` [PATCH 6/8] blk-mq-sched: add framework for MQ capable IO schedulers Jens Axboe
2016-12-20 11:55 ` Paolo Valente
2016-12-20 15:45 ` Jens Axboe
2016-12-21 2:22 ` Jens Axboe
2016-12-22 15:20 ` Paolo Valente
2016-12-22 9:59 ` Paolo Valente
2016-12-22 11:13 ` Paolo Valente
2017-01-17 2:47 ` Jens Axboe
2017-01-17 10:13 ` Paolo Valente
2017-01-17 12:38 ` Jens Axboe
2016-12-23 10:12 ` Paolo Valente
2017-01-17 2:47 ` Jens Axboe
2017-01-17 9:17 ` Paolo Valente
2016-12-17 0:12 ` [PATCH 7/8] mq-deadline: add blk-mq adaptation of the deadline IO scheduler Jens Axboe
2016-12-20 9:34 ` Paolo Valente
2016-12-20 15:46 ` Jens Axboe
2016-12-21 11:59 ` Bart Van Assche
2016-12-21 14:22 ` Jens Axboe
2016-12-22 16:07 ` Paolo Valente
2017-01-17 2:47 ` Jens Axboe
2016-12-22 16:49 ` Paolo Valente
2017-01-17 2:47 ` Jens Axboe
2017-01-20 11:07 ` Paolo Valente [this message]
2017-01-20 14:26 ` Jens Axboe
2017-01-20 13:14 ` Paolo Valente
2017-01-20 13:18 ` Paolo Valente
2017-01-20 14:28 ` Jens Axboe
2017-01-20 14:28 ` Jens Axboe
2017-02-01 11:11 ` Paolo Valente
2017-02-02 5:19 ` Jens Axboe
2017-02-02 9:19 ` Paolo Valente
2017-02-02 15:30 ` Jens Axboe
2017-02-02 21:15 ` Paolo Valente
2017-02-02 21:32 ` Jens Axboe
2017-02-07 17:27 ` Paolo Valente
2017-02-01 11:56 ` Paolo Valente
2017-02-02 5:20 ` Jens Axboe
2017-02-16 10:46 ` Paolo Valente
2017-02-16 15:35 ` Jens Axboe
2016-12-17 0:12 ` [PATCH 8/8] blk-mq-sched: allow setting of default " Jens Axboe
2016-12-19 11:32 ` [PATCHSET v4] blk-mq-scheduling framework Paolo Valente
2016-12-19 15:20 ` Jens Axboe
2016-12-19 15:33 ` Jens Axboe
2016-12-19 18:21 ` Paolo Valente
2016-12-19 21:05 ` Jens Axboe
2016-12-22 15:28 ` Paolo Valente
2017-01-17 2:47 ` Jens Axboe
2017-01-17 10:49 ` Paolo Valente
2017-01-18 16:14 ` Paolo Valente
2017-01-18 16:21 ` Jens Axboe
2017-01-23 17:04 ` Paolo Valente
2017-01-23 17:42 ` Jens Axboe
2017-01-25 8:46 ` Paolo Valente
2017-01-25 16:13 ` Jens Axboe
2017-01-26 14:23 ` Paolo Valente
2016-12-22 16:23 ` Bart Van Assche
2016-12-22 16:52 ` Omar Sandoval
2016-12-22 16:57 ` Bart Van Assche
2016-12-22 17:12 ` Omar Sandoval
2016-12-22 17:39 ` Bart Van Assche
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