From: Jens Axboe <axboe@kernel.dk>
To: Paolo Valente <paolo.valente@linaro.org>
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
ulf.hansson@linaro.org, broonie@kernel.org,
linus.walleij@linaro.org, bfq-iosched@googlegroups.com,
oleksandr@natalenko.name, khlebnikov@yandex-team.ru
Subject: Re: [PATCH BUGFIX] block, bfq: lower-bound the estimated peak rate to 1
Date: Mon, 26 Mar 2018 10:18:56 -0600 [thread overview]
Message-ID: <5035d1cf-f9ff-013f-87d8-19891d5e8df0@kernel.dk> (raw)
In-Reply-To: <20180326140624.2295-1-paolo.valente@linaro.org>
On 3/26/18 8:06 AM, Paolo Valente wrote:
> If a storage device handled by BFQ happens to be slower than 7.5 KB/s
> for a certain amount of time (in the order of a second), then the
> estimated peak rate of the device, maintained in BFQ, becomes equal to
> 0. The reason is the limited precision with which the rate is
> represented (details on the range of representable values in the
> comments introduced by this commit). This leads to a division-by-zero
> error where the estimated peak rate is used as divisor. Such a type of
> failure has been reported in [1].
>
> This commit addresses this issue by:
> 1. Lower-bounding the estimated peak rate to 1
> 2. Adding and improving comments on the range of rates representable
Applied for 4.17, thanks.
--
Jens Axboe
prev parent reply other threads:[~2018-03-26 16:19 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-26 14:06 Paolo Valente
2018-03-26 16:18 ` Jens Axboe [this message]
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