From: Jeff Moyer <jmoyer@redhat.com>
To: Mel Gorman <mgorman@suse.de>
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: Thu, 19 Jun 2014 14:38:44 -0400 [thread overview]
Message-ID: <x49y4wslp6z.fsf@segfault.boston.devel.redhat.com> (raw)
In-Reply-To: <1403079807-24690-2-git-send-email-mgorman@suse.de> (Mel Gorman's message of "Wed, 18 Jun 2014 09:23:24 +0100")
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? Also, what normal workload
has 8 or more threads doing sequential reads? (That's an honest
question.)
Cheers,
Jeff
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next prev parent reply other threads:[~2014-06-19 18:38 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 [this message]
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
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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