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SubjectRe: [PATCH 2/2] cfq-iosched: Take care of corner cases of group losing share due to deletion
On Wed, Dec 09, 2009 at 02:06:10PM -0500, Jeff Moyer wrote:
> Vivek Goyal <vgoyal@redhat.com> writes:
>
> > Reported-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
> > Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
>
> > + /*
> > + * If think times is less than a jiffy than ttime_mean=0 and above
> > + * will not be true. It might happen that slice has not expired yet
> > + * but will expire soon (4-5 ns) during select_queue(). To cover the
>
> 4-5ns? I'm not sure why you chose these numbers. Is that what you saw
> in testing?

Yes, that was the number I observed in blktrace while I was debugging
the issue.

> Anyway, I'm ok with the change, I dislike the reference to
> time when a single jiffy could be up to 10ms.
>
> Reviewed-by: Jeff Moyer <jmoyer@redhat.com>


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