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Message-ID: <x49hbkndmoc.fsf@segfault.boston.devel.redhat.com>
Date: Mon, 28 Jun 2010 14:41:55 -0400
From: Jeff Moyer <jmoyer@...hat.com>
To: Jens Axboe <axboe@...nel.dk>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] cfq: always return false from should_idle if slice_idle is set to zero
Jens Axboe <axboe@...nel.dk> writes:
> On 21/06/10 21.49, Jeff Moyer wrote:
>> Hi,
>>
>> In testing a competing fsync-ing process and a sequential reader on
>> mid-grade storage, I found that cfq was incapable of achieving the I/O
>> rates of deadline, no matter how it was tuned. Investigation, and insight
>> from Vivek (mostly the latter), led to identifying that we were still
>> idling for the last queue in the service tree.
>>
>> Modifying cfq_should_idle to not idle when slice_idle is set to zero got
>> us much closer to the performance of deadline for this workload. I have
>> one follow-on patch that gets us on-par with deadline, but I think this
>> patch stands alone.
>>
>> Comments, as always, are appreciated.
>
> This looks good.
So.... applied to which branch?
Thanks!
Jeff
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