From: Paolo Valente <paolo.valente@linaro.org>
To: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Cc: linux-block@vger.kernel.org, Ben Hutchings <ben@decadent.org.uk>
Subject: Re: blk-mq 5-8 times slower for bmap-tools
Date: Fri, 17 Aug 2018 19:42:15 +0200 [thread overview]
Message-ID: <82A59CD0-9B59-4F5B-BE9B-BCDD3FDCA177@linaro.org> (raw)
In-Reply-To: <CAPybu_3_ZJ8KopMM6fxvHXkXmdLUyqPZoXx=fx=nDYOXsvesHg@mail.gmail.com>
> Il giorno 17 ago 2018, alle ore 19:39, Ricardo Ribalda Delgado =
<ricardo.ribalda@gmail.com> ha scritto:
>=20
> Hello Paolo
> On Fri, Aug 17, 2018 at 7:35 PM Paolo Valente =
<paolo.valente@linaro.org> wrote:
>>=20
>>=20
>>=20
>>> Il giorno 17 ago 2018, alle ore 19:31, Ricardo Ribalda Delgado =
<ricardo.ribalda@gmail.com> ha scritto:
>>>=20
>>> Hello
>>>=20
>>> Coming from: =
https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=3D906328
>>>=20
>>> bmaptools is kind of a "smart dd" tool, that lets you write images
>>> very fast and securely. Since the last Debian Kernel update it has
>>> become 5-8 times slower.
>>>=20
>>> After some debugging, we have figured out that the reason for that
>>> slowness is the Multi-Queue Block IO Queueing Mechanism.
>>>=20
>>> Debian maintainer has pointed out that in the near future the single
>>> queue will be deprecated.
>>>=20
>>> My question is if we can get a similar perfomance for bmaptools with
>>> blk-mq and how?
>>>=20
>>=20
>> Have you also checked what happens after switching to a different I/O
>> scheduler for the involved drive (among none, mq-deadline, bfq and
>> kyber)?
>=20
> I have only tried mq-deadline and none (because they are enabled by
> default on Debian). Both produce results in the same range: 5-8 times
> slower.
>=20
> I could easily enable kyber:
> cat /boot/config-4.17.0-1-amd64 | grep CONFIG_MQ_IOSCHED
> CONFIG_MQ_IOSCHED_DEADLINE=3Dy
> CONFIG_MQ_IOSCHED_KYBER=3Dm
>=20
> But I left the card reader on the office, so any test would have to
> wait until monday sorry :(
>=20
Try bfq too, as it is probably the one containing also the most old
way heuristics. If bfq fails too, we will at least know that the issue
is out of the schedulers. Or in every scheduler! :)
Paolo
>=20
>>=20
>> Paolo
>>=20
>>> Thanks!
>>>=20
>>> --
>>> Ricardo Ribalda
>>=20
>=20
>=20
> --=20
> Ricardo Ribalda
next prev parent reply other threads:[~2018-08-17 20:46 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-17 17:31 blk-mq 5-8 times slower for bmap-tools Ricardo Ribalda Delgado
2018-08-17 17:35 ` Paolo Valente
2018-08-17 17:39 ` Ricardo Ribalda Delgado
2018-08-17 17:41 ` Jens Axboe
2018-08-17 17:49 ` Ricardo Ribalda Delgado
2018-08-17 21:23 ` Jens Axboe
2018-08-17 17:42 ` Paolo Valente [this message]
2018-08-17 17:52 ` Ricardo Ribalda Delgado
2018-08-17 23:43 ` Ming Lei
[not found] ` <CAPybu_2ke4usj9Qwr9iSKTymAk1510pzZnZAgLemRB+cK4Se1A@mail.gmail.com>
2018-08-20 8:30 ` Ming Lei
2018-08-20 9:04 ` Ricardo Ribalda Delgado
2018-08-20 9:55 ` Ming Lei
2018-08-20 9:56 ` Ricardo Ribalda Delgado
2018-08-20 10:15 ` Ming Lei
2018-08-20 11:42 ` Ming Lei
2018-08-20 11:45 ` Ming Lei
2018-08-22 19:22 ` Ben Hutchings
2018-08-22 22:02 ` Ming Lei
2018-08-23 0:51 ` Ben Hutchings
2018-08-23 2:17 ` Ming Lei
2018-08-23 6:29 ` Ricardo Ribalda Delgado
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