From: Tracy Reed <treed@ultraviolet.org>
To: dm-crypt@saout.de
Subject: Re: [dm-crypt] poor mysqldump performance
Date: Thu, 23 Feb 2012 18:55:10 -0800 [thread overview]
Message-ID: <20120224025510.GL22456@tracyreed.org> (raw)
In-Reply-To: <20120224012954.GJ17572@agk-dp.fab.redhat.com>
On Fri, Feb 24, 2012 at 01:29:54AM +0000, Alasdair G Kergon spake thusly:
> Have you done much tuning, in particular /sys/block/<devices>/queue/nr_requests ?
>
> http://www.redbooks.ibm.com/redpapers/pdfs/redp4285.pdf remains a good background
> read.
Given that a non-dmcrypt mysqldump on the same disks (different logical volume)
finishes and 15 minutes and a dmcrypt mysql backup happens in 30 minutes any
tuning being done would have to be dmcrypt-specific and affect something in the
dmcrypt layer or above, correct?
nr_requests only exists for the physical disk device. Just for kicks I just
bumped it up to 8192 from the default 1024 and ran my test again. Same
performance: Twice as slow as without dmcrypt.
--
Tracy Reed
prev parent reply other threads:[~2012-02-24 2:55 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-23 22:23 [dm-crypt] poor mysqldump performance Tracy Reed
2012-02-23 23:10 ` Arno Wagner
2012-02-23 23:59 ` Tracy Reed
2012-02-24 8:18 ` Milan Broz
2012-02-24 19:07 ` Tracy Reed
2012-02-24 20:05 ` Arno Wagner
2012-02-24 22:30 ` Tracy Reed
2012-02-25 2:13 ` Arno Wagner
2012-02-24 1:29 ` Alasdair G Kergon
2012-02-24 2:55 ` Tracy Reed [this message]
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