From: Christoph Hellwig <hch@infradead.org>
To: Dominik Brodowski <linux@dominikbrodowski.net>,
Christoph Hellwig <hch@infradead.org>,
linux-raid@vger.kernel.org, xfs@oss.sgi.com,
linux-kernel@vger.kernel.org
Subject: Re: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs
Date: Wed, 4 Aug 2010 05:21:22 -0400 [thread overview]
Message-ID: <20100804092122.GA2998@infradead.org> (raw)
In-Reply-To: <20100804091317.GA27779@isilmar-3.linta.de>
On Wed, Aug 04, 2010 at 11:13:17AM +0200, Dominik Brodowski wrote:
> > show these problems?
>
> No, 2.6.31 to 2.6.34 show similar behaviour.
Ok, so it's been around for a while. Can you test the write speed of
each individual device layer by doing a large read from it, using:
dd if=<device> of=/dev/null bs=8k iflag=direct
where device starts with the /dev/sda* device, and goes up to the MD
device, the dm-crypt device and the LV. And yes, it's safe to read
from the device while it's otherwise mounted/used.
next prev parent reply other threads:[~2010-08-04 9:21 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 [this message]
2010-08-04 9:16 ` Michael Monnerie
2010-08-04 10:25 ` Dominik Brodowski
2010-08-04 11:18 ` Christoph Hellwig
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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