linux-kernel - Re: [PATCH] block: BFQ default for single queue devices

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Message-Id: <466C47DB-02D7-490C-91E3-8C7AA41B8D79@linaro.org>
Date:   Thu, 4 Oct 2018 22:19:34 +0200
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Alan Cox <gnomes@...rguk.ukuu.org.uk>
Cc:     Bart Van Assche <bvanassche@....org>, Jens Axboe <axboe@...nel.dk>,
        Linus Walleij <linus.walleij@...aro.org>,
        linux-block <linux-block@...r.kernel.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        linux-mtd@...ts.infradead.org, Pavel Machek <pavel@....cz>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Richard Weinberger <richard@....at>,
        Artem Bityutskiy <dedekind1@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Jan Kara <jack@...e.cz>, Andreas Herrmann <aherrmann@...e.com>,
        Mel Gorman <mgorman@...e.com>,
        Chunyan Zhang <zhang.chunyan@...aro.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Oleksandr Natalenko <oleksandr@...alenko.name>,
        Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH] block: BFQ default for single queue devices



> Il giorno 04 ott 2018, alle ore 21:25, Alan Cox <gnomes@...rguk.ukuu.org.uk> ha scritto:
> 
>> I agree with Jens that it's best to leave it to the Linux distributors to
>> select a default I/O scheduler.
> 
> That assumes such a thing exists.

Well, as of now the default is more or less in the Schrdinger's cat state :)

Metaphors apart, I do agree with your point.  As for me, what you
point out is one of the core issues at stake here.

Thanks,
Paolo

> The kernel knows what devices it is
> dealing with. The kernel 'default' ought to be 'whatever is usually best
> for this device'. A distro cannot just pick a correct single default
> because NVME and USB sticks are both normal and rather different in needs.
> 
> Alan