From: Jens Axboe <axboe@kernel.dk>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] cfq: always return false from should_idle if slice_idle is set to zero
Date: Mon, 21 Jun 2010 22:00:10 +0200 [thread overview]
Message-ID: <4C1FC4CA.7030007@kernel.dk> (raw)
In-Reply-To: <1277149789-4493-2-git-send-email-jmoyer@redhat.com>
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.
--
Jens Axboe
next prev parent reply other threads:[~2010-06-21 20:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-21 19:49 [PATCH 0/2] cfq: fixes to bring cfq in line with deadline performance for mid- to high-end storage Jeff Moyer
2010-06-21 19:49 ` [PATCH 1/2] cfq: always return false from should_idle if slice_idle is set to zero Jeff Moyer
2010-06-21 20:00 ` Jens Axboe [this message]
2010-06-28 18:41 ` Jeff Moyer
2010-06-28 18:50 ` Jens Axboe
2010-06-28 18:54 ` Jeff Moyer
2010-06-21 23:05 ` Vivek Goyal
2010-06-21 19:49 ` [PATCH 2/2] cfq: allow dispatching of both sync and async I/O together Jeff Moyer
2010-06-21 19:59 ` Jens Axboe
2010-06-21 20:05 ` Jeff Moyer
2010-06-21 23:22 ` Vivek Goyal
2010-06-22 4:07 ` Vivek Goyal
2010-06-22 12:45 ` Jeff Moyer
2010-06-22 13:18 ` Vivek Goyal
2010-06-22 13:21 ` Jens Axboe
2010-06-22 14:24 ` Vivek Goyal
2010-06-22 14:27 ` Jeff Moyer
2010-06-28 18:40 ` Jeff Moyer
2010-06-28 18:48 ` Jens Axboe
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