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From: Bart Van Assche <bvanassche@acm.org>
To: Paolo Valente <paolo.valente@linaro.org>, Jens Axboe <axboe@kernel.dk>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	linux-block <linux-block@vger.kernel.org>,
	linux-mmc <linux-mmc@vger.kernel.org>,
	linux-mtd@lists.infradead.org, Pavel Machek <pavel@ucw.cz>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Richard Weinberger <richard@nod.at>,
	Artem Bityutskiy <dedekind1@gmail.com>,
	Adrian Hunter <adrian.hunter@intel.com>, Jan Kara <jack@suse.cz>,
	Andreas Herrmann <aherrmann@suse.com>,
	Mel Gorman <mgorman@suse.com>,
	Chunyan Zhang <zhang.chunyan@linaro.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	'Paolo Valente' via bfq-iosched <bfq-iosched@googlegroups.com>,
	Oleksandr Natalenko <oleksandr@natalenko.name>,
	 Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH] block: BFQ default for single queue devices
Date: Wed, 03 Oct 2018 08:54:51 -0700	[thread overview]
Message-ID: <1538582091.205649.20.camel@acm.org> (raw)
In-Reply-To: <B5321A64-8A1A-42FF-A337-F4524BDA179B@linaro.org>

On Wed, 2018-10-03 at 08:29 +0200, Paolo Valente wrote:
> [1] https://lkml.org/lkml/2017/2/21/791
> [2] http://algo.ing.unimo.it/people/paolo/disk_sched/results.php
> [3] https://lwn.net/Articles/763603/

>From [2]: "BFQ loses about 18% with only random readers, because the number
of IOPS becomes so high that the execution time and parallel efficiency of
the schedulers becomes relevant." Since the number of I/O patterns for which
results are available on [2] is limited and since the number of devices for
which test results are available on [2] is limited (e.g. RAID is missing),
there might be other cases in which configuring BFQ as the default would
introduce a regression.

I agree with Jens that it's best to leave it to the Linux distributors to
select a default I/O scheduler.

Bart.

WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <bvanassche@acm.org>
To: Paolo Valente <paolo.valente@linaro.org>, Jens Axboe <axboe@kernel.dk>
Cc: Linus Walleij <linus.walleij@linaro.org>,
	linux-block <linux-block@vger.kernel.org>,
	linux-mmc <linux-mmc@vger.kernel.org>,
	linux-mtd@lists.infradead.org, Pavel Machek <pavel@ucw.cz>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Richard Weinberger <richard@nod.at>,
	Artem Bityutskiy <dedekind1@gmail.com>,
	Adrian Hunter <adrian.hunter@intel.com>, Jan Kara <jack@suse.cz>,
	Andreas Herrmann <aherrmann@suse.com>,
	Mel Gorman <mgorman@suse.com>,
	Chunyan Zhang <zhang.chunyan@linaro.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	'Paolo Valente' via bfq-iosched  <bfq-iosched@googlegroups.com>,
	Oleksandr Natalenko <oleksandr@natalenko.name>,
	Mark Brown <broonie@kernel.org>
Subject: Re: [PATCH] block: BFQ default for single queue devices
Date: Wed, 03 Oct 2018 08:54:51 -0700	[thread overview]
Message-ID: <1538582091.205649.20.camel@acm.org> (raw)
In-Reply-To: <B5321A64-8A1A-42FF-A337-F4524BDA179B@linaro.org>

On Wed, 2018-10-03 at 08:29 +0200, Paolo Valente wrote:
> [1] https://lkml.org/lkml/2017/2/21/791
> [2] http://algo.ing.unimo.it/people/paolo/disk_sched/results.php
> [3] https://lwn.net/Articles/763603/

From [2]: "BFQ loses about 18% with only random readers, because the number
of IOPS becomes so high that the execution time and parallel efficiency of
the schedulers becomes relevant." Since the number of I/O patterns for which
results are available on [2] is limited and since the number of devices for
which test results are available on [2] is limited (e.g. RAID is missing),
there might be other cases in which configuring BFQ as the default would
introduce a regression.

I agree with Jens that it's best to leave it to the Linux distributors to
select a default I/O scheduler.

Bart.

  parent reply	other threads:[~2018-10-03 15:54 UTC|newest]

Thread overview: 89+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-02 12:43 [PATCH] block: BFQ default for single queue devices Linus Walleij
2018-10-02 12:43 ` Linus Walleij
2018-10-02 14:31 ` Jens Axboe
2018-10-02 14:31   ` Jens Axboe
2018-10-02 14:45   ` Linus Walleij
2018-10-02 14:45     ` Linus Walleij
2018-10-03  6:29   ` Paolo Valente
2018-10-03  6:29     ` Paolo Valente
2018-10-03  6:53     ` Linus Walleij
2018-10-03 13:25       ` Jan Kara
2018-10-04  7:45         ` Johannes Thumshirn
2018-10-04  7:45           ` Johannes Thumshirn
2018-10-04  8:24           ` Andreas Herrmann
2018-10-03  7:05     ` Artem Bityutskiy
2018-10-03  7:18       ` Linus Walleij
2018-10-03  7:42         ` Damien Le Moal
2018-10-03  7:42           ` Damien Le Moal
2018-10-03  8:28           ` Linus Walleij
2018-10-03  8:53             ` Damien Le Moal
2018-10-03  8:53               ` Damien Le Moal
2018-10-03  8:53               ` Damien Le Moal
2018-10-03 15:53             ` Paolo Valente
2018-10-03 15:53               ` Paolo Valente
2018-10-03 17:34               ` Bryan Gurney
2018-10-04  8:21                 ` Linus Walleij
2018-10-04  9:56                 ` Ulf Hansson
2018-10-03 12:51           ` Christoph Hellwig
2018-10-03 12:51             ` Christoph Hellwig
2018-10-03 14:58             ` Bart Van Assche
2018-10-03 14:58               ` Bart Van Assche
2018-10-03 15:01               ` Christoph Hellwig
2018-10-03 15:01                 ` Christoph Hellwig
2018-10-03 15:15                 ` Bart Van Assche
2018-10-03 15:15                   ` Bart Van Assche
2018-10-05  6:24                   ` Christoph Hellwig
2018-10-05  6:24                     ` Christoph Hellwig
2018-10-03 15:52           ` Paolo Valente
2018-10-03 15:52             ` Paolo Valente
2018-10-03 15:52             ` Paolo Valente
2018-10-03 11:49     ` Oleksandr Natalenko
2018-10-03 11:49       ` Oleksandr Natalenko
2018-10-03 14:51       ` Mark Brown
2018-10-03 15:55       ` Paolo Valente
2018-10-03 15:55         ` Paolo Valente
2018-10-03 16:00         ` Bart Van Assche
2018-10-03 16:04           ` Paolo Valente
2018-10-03 16:04             ` Paolo Valente
2018-10-04  7:38         ` Jan Kara
2018-10-04  8:14       ` Linus Walleij
2018-10-04 10:13         ` Mark Brown
2018-10-04 15:10           ` Bart Van Assche
2018-10-04 15:26             ` Mark Brown
2018-10-05  9:49         ` Pavel Machek
2018-10-04  8:25       ` Linus Walleij
2018-10-03 15:54     ` Bart Van Assche [this message]
2018-10-03 15:54       ` Bart Van Assche
2018-10-03 16:02       ` Paolo Valente
2018-10-03 16:02         ` Paolo Valente
2018-10-03 16:09         ` Paolo Valente
2018-10-03 17:22         ` Paolo Valente
2018-10-03 17:22           ` Paolo Valente
2018-10-04 19:25       ` Alan Cox
2018-10-04 19:25         ` Alan Cox
2018-10-04 20:09         ` Bart Van Assche
2018-10-04 20:39           ` Paolo Valente
2018-10-04 20:39             ` Paolo Valente
2018-10-04 22:42             ` Bart Van Assche
2018-10-05  9:16               ` Jan Kara
2018-10-06  3:12                 ` Bart Van Assche
2018-10-06  6:46                   ` Paolo Valente
2018-10-06  6:46                     ` Paolo Valente
2018-10-06  6:46                     ` Paolo Valente
2018-10-06 16:20                     ` Bart Van Assche
2018-10-06 16:20                       ` Bart Van Assche
2018-10-06 16:46                       ` Paolo Valente
2018-10-06 16:46                         ` Paolo Valente
2018-10-06 16:46                         ` Paolo Valente
2018-10-05  9:28               ` Paolo Valente
2018-10-05  9:28                 ` Paolo Valente
2018-10-05  6:24           ` Artem Bityutskiy
2018-10-04 20:19         ` Paolo Valente
2018-10-04 20:19           ` Paolo Valente
2018-10-02 21:28 ` Richard Weinberger
2018-10-02 21:28   ` Richard Weinberger
2018-10-03 15:51 ` Paolo Valente
2018-10-03 15:51   ` Paolo Valente
2018-10-03 15:51   ` Paolo Valente
2018-10-05  8:04 ` Pavel Machek
2018-10-05  8:04   ` Pavel Machek

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