Date: Fri, 17 Feb 2012 17:34:20 -0500
From: Vivek Goyal <vgoyal@redhat.com>
To: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <koverstreet@google.com>, axboe@kernel.dk,
        ctalbott@google.com, rni@google.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/9] block: implement bio_associate_current()
Message-ID: <20120217223420.GJ26620@redhat.com>
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 <20120217011907.GA15073@google.com>
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On Fri, Feb 17, 2012 at 02:14:06PM -0800, Tejun Heo wrote:

[..]
> If the associated blkcg is used consistently through block layer, it
> might be better but cfq doesn't even do that.  It has its own icq ->
> blkcg mapping, which it initializes on first cfqq association.  It
> even ignores tasks migrating to a different cgroup and keeps using
> whatever cgroup the task first issued IOs on. :(

Nope. We make note of task migration and drop cic->cfqq association
and establish a new association where new cfqq is part of new cgroup.
(ioc_cgroup_changed()).

In the past people have raised the issue of retaining the notion of
iopriority while dm targets are operating in between. This patchset
will help for that case.

Thanks
Vivek
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