From: Mel Gorman <mgorman@suse.de>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Linux-FSDevel <linux-fsdevel@vger.kernel.org>,
Jan Kara <jack@suse.cz>, Johannes Weiner <hannes@cmpxchg.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCH 1/4] cfq: Increase default value of target_latency
Date: Fri, 20 Jun 2014 12:28:57 +0100 [thread overview]
Message-ID: <20140620112857.GF10819@suse.de> (raw)
In-Reply-To: <x49y4wslp6z.fsf@segfault.boston.devel.redhat.com>
On Thu, Jun 19, 2014 at 02:38:44PM -0400, Jeff Moyer wrote:
> Mel Gorman <mgorman@suse.de> writes:
>
> > The existing CFQ default target_latency results in very poor performance
> > for larger numbers of threads doing sequential reads. While this can be
> > easily described as a tuning problem for users, it is one that is tricky
> > to detect. This patch the default on the assumption that people with access
> > to expensive fast storage also know how to tune their IO scheduler.
> >
> > The following is from tiobench run on a mid-range desktop with a single
> > spinning disk.
> >
> > 3.16.0-rc1 3.16.0-rc1 3.0.0
> > vanilla cfq600 vanilla
> > Mean SeqRead-MB/sec-1 121.88 ( 0.00%) 121.60 ( -0.23%) 134.59 ( 10.42%)
> > Mean SeqRead-MB/sec-2 101.99 ( 0.00%) 102.35 ( 0.36%) 122.59 ( 20.20%)
> > Mean SeqRead-MB/sec-4 97.42 ( 0.00%) 99.71 ( 2.35%) 114.78 ( 17.82%)
> > Mean SeqRead-MB/sec-8 83.39 ( 0.00%) 90.39 ( 8.39%) 100.14 ( 20.09%)
> > Mean SeqRead-MB/sec-16 68.90 ( 0.00%) 77.29 ( 12.18%) 81.64 ( 18.50%)
>
> Did you test any workloads other than this?
dd tests were inconclusive due to high variability. The dbench results
hadn't come through but regression tests there indicate that it has
regressed for high numbers of clients. I know sequential reads of
benchmarks like bonnie++ have also regressed but I have not reverified
the results yet.
> Also, what normal workload
> has 8 or more threads doing sequential reads? (That's an honest
> question.)
>
File servers, mail servers, streaming media servers with multiple users,
multi-user systems
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2014-06-20 11:28 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-18 8:23 [PATCH 0/4] Improve sequential read throughput Mel Gorman
2014-06-18 8:23 ` [PATCH 1/4] cfq: Increase default value of target_latency Mel Gorman
2014-06-19 18:38 ` Jeff Moyer
2014-06-19 21:42 ` Dave Chinner
2014-06-20 11:30 ` Mel Gorman
2014-06-21 0:39 ` Dave Chinner
2014-06-20 11:28 ` Mel Gorman [this message]
2014-06-18 8:23 ` [PATCH 2/4] mm: pagemap: Avoid unnecessary overhead when tracepoints are deactivated Mel Gorman
2014-06-18 8:23 ` [PATCH 3/4] mm: page_alloc: Reset fair zone allocation policy when batch counts are expired Mel Gorman
2014-06-18 20:01 ` Johannes Weiner
2014-06-18 21:57 ` Mel Gorman
2014-06-19 18:18 ` Johannes Weiner
2014-06-18 8:23 ` [PATCH 4/4] mm: page_alloc: Reduce cost of dirty zone balancing Mel Gorman
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