linux-kernel - Re: [PATCH 2/2] block, bfq: delete "bfq" prefix from cgroup filenames

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Message-Id: <4F416823-855F-4091-90B9-92253BF189FA@linaro.org>
Date:   Wed, 18 Sep 2019 18:19:42 +0200
From:   Paolo Valente <paolo.valente@...aro.org>
To:     Tejun Heo <tj@...nel.org>
Cc:     Jens Axboe <axboe@...nel.dk>,
        linux-block <linux-block@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        noreply-spamdigest via bfq-iosched 
        <bfq-iosched@...glegroups.com>, oleksandr@...alenko.name,
        cgroups@...r.kernel.org, Angelo Ruocco <angeloruocco90@...il.com>
Subject: Re: [PATCH 2/2] block, bfq: delete "bfq" prefix from cgroup filenames



> Il giorno 18 set 2019, alle ore 17:19, Tejun Heo <tj@...nel.org> ha scritto:
> 
> Hello,
> 
> On Wed, Sep 18, 2019 at 07:18:50AM +0200, Paolo Valente wrote:
>> A solution that both fulfills userspace request and doesn't break
>> anything for hypothetical users of the current interface already made
>> it to mainline, and Linus liked it too.  It is:
> 
> Linus didn't like it.  The implementation was a bit nasty.  That was
> why it became a subject in the first place.
> 
>> 19e9da9e86c4 ("block, bfq: add weight symlink to the bfq.weight cgroup parameter")
>> 
>> But it was then reverted on Tejun's request to do exactly what we
>> don't want do any longer now:
>> cf8929885de3 ("cgroup/bfq: revert bfq.weight symlink change")
> 
> Note that the interface was wrong at the time too.
> 
>> So, Jens, Tejun, can we please just revert that revert?
> 
> I think presenting both io.weight and io.bfq.weight interfaces are
> probably the best course of action at this point but why does it have
> to be a symlink?  What's wrong with just creating another file with
> the same backing function?
> 

I think a symlink would be much clearer for users, given the confusion
already caused by two names for the same parameter.  But let's hear
others' opinion too.

Thanks,
Paolo

> Thanks.
> 
> -- 
> tejun