From: Christoph Hellwig <hch@infradead.org>
To: Dominik Brodowski <linux@dominikbrodowski.net>,
Michael Monnerie <michael.monnerie@is.it-management.at>,
Christoph Hellwig <hch@infradead.org>,
linux-raid@vger.kernel.org, xfs@oss.sgi
Subject: Re: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs
Date: Wed, 4 Aug 2010 07:18:03 -0400 [thread overview]
Message-ID: <20100804111803.GA32643@infradead.org> (raw)
In-Reply-To: <20100804102526.GB13766@isilmar-3.linta.de>
On Wed, Aug 04, 2010 at 12:25:26PM +0200, Dominik Brodowski wrote:
> Hey,
>
> many thanks for your feedback. It seems the crypto step is the culprit:
>
> Reading 1.1 GB with dd, iflag=direct, bs=8k:
>
> /dev/sd* 35.3 MB/s ( 90 %)
> /dev/md* 39.1 MB/s (100 %)
> /dev/mapper/md*_crypt 3.9 MB/s ( 10 %)
> /dev/mapper/vg1-* 3.9 MB/s ( 10 %)
>
> The "good" news: it also happens on my notebook, even though it has a
> different setup (no raid, disk -> lv/vg -> crypt). On my notebook, I'm
> more than happy to test out different kernel versions, patches etc.
>
> /dev/sd* 17.7 MB/s (100 %)
> /dev/mapper/vg1-* 16.2 MB/s ( 92 %)
> /dev/mapper/*_crypt 3.1 MB/s ( 18 %)
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?
next prev parent reply other threads:[~2010-08-04 11:18 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-04 7:35 How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs Dominik Brodowski
2010-08-04 8:50 ` Christoph Hellwig
2010-08-04 9:13 ` Dominik Brodowski
2010-08-04 9:21 ` Christoph Hellwig
2010-08-04 9:16 ` Michael Monnerie
2010-08-04 10:25 ` Dominik Brodowski
2010-08-04 11:18 ` Christoph Hellwig [this message]
2010-08-04 11:24 ` Dominik Brodowski
2010-08-04 11:53 ` Mikael Abrahamsson
2010-08-04 12:56 ` Mike Snitzer
2010-08-04 22:24 ` Neil Brown
[not found] ` <20100804111803.GA32643__39273.3621680692$1280923964$gmane$org@infradead.org>
2010-08-04 17:43 ` Andi Kleen
2010-08-04 20:33 ` Valdis.Kletnieks
2010-08-05 9:31 ` direct-io regression [Was: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs] Dominik Brodowski
2010-08-05 11:32 ` Chris Mason
2010-08-05 12:36 ` Josef Bacik
2010-08-05 15:35 ` Dominik Brodowski
2010-08-05 15:39 ` Chris Mason
2010-08-05 15:53 ` Dominik Brodowski
2010-08-05 16:35 ` Dominik Brodowski
2010-08-05 20:47 ` Performance impact of CONFIG_DEBUG? direct-io test case Dominik Brodowski
2010-08-05 20:54 ` Performance impact of CONFIG_SCHED_MC? " Dominik Brodowski
2010-08-05 18:58 ` direct-io regression [Was: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs] Jeff Moyer
2010-08-05 19:01 ` Chris Mason
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