From: "Holger Hoffstätte" <holger@applied-asynchrony.com>
To: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
linux-block@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
Paolo Valente <paolo.valente@linaro.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH RFC] block, bfq: set default slice_idle to zero for non-rotational devices
Date: Thu, 1 Nov 2018 20:06:09 +0100 [thread overview]
Message-ID: <317076f7-f84f-c08f-5fb5-b227094cabfd@applied-asynchrony.com> (raw)
In-Reply-To: <154109421062.925711.4117729151502021084.stgit@buzz>
On 11/01/18 18:43, Konstantin Khlebnikov wrote:
> With default 8ms idle slice BFQ is up to 10 times slower than CFQ
> for massive random read workloads for common SATA SSD.
>
> For now zero idle slice gives better out of box experience.
> CFQ employs this since commit 41c0126b3f22 ("block: Make CFQ default
> to IOPS mode on SSDs")
Well, that's interesting because 3 years ago I made the same suggestion
and was told that BFQ's heuristics automagically make it not idle when
rotational=0. Did you actually benchmark this? I just tried and don't
get a noticeable performance difference with slice_idle=0 compared to
deadline.
Discussion link:
https://groups.google.com/forum/#!msg/bfq-iosched/iRMw2n3kYLY/6l9cIm3TBgAJ
curious..
Holger
next prev parent reply other threads:[~2018-11-01 19:06 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 17:43 Konstantin Khlebnikov
2018-11-01 19:06 ` Holger Hoffstätte [this message]
2018-11-02 18:18 ` Paolo Valente
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