Re: [PATCH/RFC 0/4] cfq: implement merging and breaking up of cfq_queues

From: Jeff Moyer
Date: Mon Oct 26 2009 - 11:01:57 EST


Jens Axboe <jens.axboe@xxxxxxxxxx> writes:

> On Mon, Oct 26 2009, Jeff Moyer wrote:
>> Corrado Zoccolo <czoccolo@xxxxxxxxx> writes:
>>
>> > Hi Jeff,
>> > this series looks good.
>>
>> Hi, Corrado. Thanks again for the review!
>>
>> > I like in particular the fact that you move seekiness detection in the cfqq.
>> > This can help with processes that issue sequential reads and seeky
>> > writes, or vice versa.
>> > Probably, also the think time could be made per-cfqq, so that the
>> > decision whether we should idle for a given cfqq is more precise.
>>
>> I'll have to think about that one. It would be good to know Jens'
>> opinion on the matter, too.
>
> Your implementation looks fine, as usual I'm mostly worried about
> performance impact and suitability (I hate having to work around
> issues). But the win is so large in some cases that we should just go
> ahead and merge it for .33, so I'll queue it up.

Great, thanks for the review. In this case, however, I was wondering
what your opinion was about moving the think time calculation to be per
cfqq. ;-)

> It would be nice to fix the in-kernel problem with NFS, since that is
> doable.

I'll see if I can get someone motivated to work on that. I'm not sure
that I can devote much time to the issue myself, unfortunately.

Cheers,
Jeff
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