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Date:   Fri, 30 Nov 2018 10:42:56 -0800
From:   Tejun Heo <tj@kernel.org>
To:     Paolo Valente <paolo.valente@linaro.org>
Cc:     'Paolo Valente' via bfq-iosched <bfq-iosched@googlegroups.com>,
        Jens Axboe <axboe@kernel.dk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Li Zefan <lizefan@huawei.com>,
        Angelo Ruocco <angeloruocco90@gmail.com>,
        Dennis Zhou <dennis@kernel.org>,
        Josef Bacik <josef@toxicpanda.com>,
        Liu Bo <bo.liu@linux.alibaba.com>,
        Bart Van Assche <bvanassche@acm.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
        ulf.hansson@linaro.org, linus.walleij@linaro.org,
        broonie@kernel.org, oleksandr@natalenko.name,
        cgroups@vger.kernel.org, linux-doc@vger.kernel.org,
        Jonathan Corbet <corbet@lwn.net>
Subject: Re: [PATCH V2 00/10] unify the interface of the proportional-share
 policy in blkio/io
Message-ID: <20181130184256.GI2509588@devbig004.ftw2.facebook.com>
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Hello, Paolo.

On Fri, Nov 30, 2018 at 07:23:24PM +0100, Paolo Valente wrote:
> > Then we understood that exactly the same happens with throttling, in
> > case the latter is activated on different devices w.r.t. bfq.
> > 
> > In addition, the same may happen, in the near future, with the
> > bandwidth controller Josef is working on.  If the controller can be
> > configured per device, as with throttling, then statistics may differ,
> > for the same interface files, between bfq, throttling and that
> > controller.

So, regardless of how all these are implemented, what's presented to
user should be consistent and clear.  There's no other way around it.
Only what's relevant should be visible to userspace.

> have you had time to look into this?  Any improvement to this
> interface is ok for us. We are only interested in finally solving this
> interface issue, as, for what concerns us directly, it has been
> preventing legacy code to use bfq for years.

Unfortunately, I don't have any implementation proposal, but we can't
show things this way to userspace.

Thanks.

-- 
tejun