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Message-ID: <alpine.DEB.1.10.1008041351100.19930@uplift.swm.pp.se>
Date: Wed, 4 Aug 2010 13:53:03 +0200 (CEST)
From: Mikael Abrahamsson <swmike@....pp.se>
To: Christoph Hellwig <hch@...radead.org>
cc: Dominik Brodowski <linux@...inikbrodowski.net>,
Michael Monnerie <michael.monnerie@...it-management.at>,
linux-raid@...r.kernel.org, xfs@....sgi.com,
linux-kernel@...r.kernel.org, dm-devel@...hat.com
Subject: Re: How to track down abysmal performance ata - raid1 - crypto -
vg/lv - xfs
On Wed, 4 Aug 2010, Christoph Hellwig wrote:
> The good news is that you have it tracked down, the bad news is that I
> know very little about dm-crypt. Maybe the issue is the single threaded
> decryption in dm-crypt? Can you check how much CPU time the dm crypt
> kernel thread uses?
I'm not sure it's that. I have a Core i5 with AES-NI and that didn't
significantly increase my overall performance, as it's not there the
bottleneck is (at least in my system).
I earlier sent out an email wondering if someone could shed some light on
how scheduling, block caching and read-ahead works together when one does
disks->md->crypto->lvm->fs, becase that's a lot of layers and potentially
a lot of unneeded buffering, readahead and scheduling magic?
--
Mikael Abrahamsson email: swmike@....pp.se
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