From: Dan Williams <dan.j.williams@intel.com>
To: neilb@suse.de, akpm@linux-foundation.org
Cc: raziebe@gmail.com, linux-raid@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [-mm PATCH 0/2] 74% decrease in dispatched writes, stripe-queue take3
Date: Fri, 13 Jul 2007 15:35:42 -0700 [thread overview]
Message-ID: <20070713223257.25202.74399.stgit@dwillia2-linux.ch.intel.com> (raw)
Neil, Andrew,
The following patches replace the stripe-queue patches currently in -mm.
Following your suggestion, Neil, I gathered blktrace data on the number
of reads generated by sequential write stimulus. It turns out that
reduced pre-reading is not the cause of the performance increase, but
rather increased write merging. The data, in patch #1, shows a 74%
decrease in the number of dispatched writes. I can only assume that
this is the explanation for the 65% throughput improvement, because the
occurrence of reads actually increased with these patches applied.
This take also fixes observed data corruption while running i/o to a
synching array (it was wrong to move the flags parameter from r5dev to
r5_queue_dev as things could get out of sync... reverted). Next step is
to test reshape under this new queuing model.
Regards,
Dan
next reply other threads:[~2007-07-13 22:35 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-07-13 22:35 Dan Williams [this message]
2007-07-13 22:35 ` [-mm PATCH 1/2] raid5: add the stripe_queue object for tracking raid io requests (take2) Dan Williams
2007-07-13 22:35 ` [-mm PATCH 2/2] raid5: use stripe_queues to prioritize the "most deserving" requests (take3) Dan Williams
2007-07-13 22:54 ` [-mm PATCH 0/2] 74% decrease in dispatched writes, stripe-queue take3 Andrew Morton
2007-07-13 22:57 ` Williams, Dan J
2007-07-13 23:01 ` Andrew Morton
2007-07-13 23:28 ` Williams, Dan J
2007-07-14 0:01 ` Andrew Morton
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