Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames

From: Paolo Valente <paolo.valente@linaro.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Johannes Thumshirn <jthumshirn@suse.de>,
	linux-block <linux-block@vger.kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Linus Walleij <linus.walleij@linaro.org>,
	Mark Brown <broonie@kernel.org>,
	'Paolo Valente' via bfq-iosched  <bfq-iosched@googlegroups.com>,
	Oleksandr Natalenko <oleksandr@natalenko.name>,
	Angelo Ruocco <angeloruocco90@gmail.com>,
	lennart@poettering.net, mkoutny@suse.cz
Subject: Re: [PATCH 1/1] block, bfq: delete "bfq" prefix from cgroup filenames
Date: Mon, 8 Apr 2019 19:01:18 +0200	[thread overview]
Message-ID: <377E06A7-14D7-4AC6-AD07-AEB691E00DEA@linaro.org> (raw)
In-Reply-To: <ef1481e8-c664-5f17-4a19-bb90daabc0b7@kernel.dk>

> Il giorno 8 apr 2019, alle ore 17:17, Jens Axboe <axboe@kernel.dk> ha scritto:
> 
> On 4/8/19 9:14 AM, Paolo Valente wrote:
>> 
>> 
>>> Il giorno 8 apr 2019, alle ore 17:08, Johannes Thumshirn <jthumshirn@suse.de> ha scritto:
>>> 
>>> On Mon, Apr 08, 2019 at 09:05:19AM -0600, Jens Axboe wrote:
>>>> I did consider that, and that would be doable. But honestly, I'm having a
>>>> hard time seeing what issue we are attempting to fix by doing this.
>>> 
>>> Yeah, I guess the real fix would be to update the documentation and the
>>> expectations user-space has. Including eventual re-write of some udev rules or
>>> whatever is facing these files. But to me that sounds more like a systemd or
>>> even distro thing than a kernel thing.
>>> 
>> 
>> Unfortunately the user-space people I have interacted with find crazy
>> to have to change their software to call bfq.weight the weight of a
>> group.  And are not willing to do it [1].
> 
> Then you need to educate them.

I'm not sure that educate is the right verb (I don't like the current
messy solution either).  But I'll do my best to inform people when
I'll have the opportunity to do it.

> Some of the issues were called out years
> ago, at the time when we could have potentially renamed.

Yeah, a good window was 5.0, and at that time we tried with a more
general solution.  But we failed.

> A rename now
> will solve nothing.
> 

I see your point, but I don't agree this rename would solve nothing.
The real bad thing is not having done this before.  Changing names
that nobody uses, to names that everybody already uses, but wrongly,
would instantaneously improve the situation a lot.  And it is what
userspace already asked explicitly for [1].  Without this simple
change, it will take a lot for all the inconsistent documentation
spread around the world to be synced.  And for all legacy software to
be changed, assuming it will all be changed.

Paolo

[1] https://github.com/systemd/systemd/issues/7057

> -- 
> Jens Axboe