Re: [PATCH 1/2] cfq: always return false from should_idle if slice_idle is set to zero

From: Jeff Moyer
Date: Mon Jun 28 2010 - 14:54:42 EST

Jens Axboe <axboe@xxxxxxxxx> writes:

> On 28/06/10 20.41, Jeff Moyer wrote:
>> Jens Axboe <axboe@xxxxxxxxx> 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?
> Not applied yet, unless I explicitly say it's applied, then it's not
> necessarily in any public git tree yet. But this will go into .35.

OK, thanks for the clarification.

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