Re: [PATCH 7/9] block: implement bio_associate_current()

[Tejun Heo]

Hey, Vivek.

On Fri, Feb 17, 2012 at 05:51:26PM -0500, Vivek Goyal wrote:
> Otherwise on every IO, we will end up comparing submitting tasks's
> cgroup and cic/cfqq's cgroup.

But how much is that different from checking CHANGED bit on each IO?
I mean, we can just do sth like cfqg->blkg->blkcg == bio_blkcg(bio).
It isn't expensive.

> Also this will create problems, if two threads sharing io context are
> in two different cgroups. We will frequently end up changing the
> association.

blkcg doesn't allow that anyway (it tries but is racy) and I actually
was thinking about sending a RFC patch to kill CLONE_IO.

Thanks.

-- 
tejun
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