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Re: [dm-devel] direct-io regression [Was: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs]
- From: Chris Mason <chris mason oracle com>
- To: Jeff Moyer <jmoyer redhat com>
- Cc: Michael Monnerie <michael monnerie is it-management at>, linux-raid vger kernel org, Valdis Kletnieks vt edu, linux-kernel vger kernel org, Dominik Brodowski <linux dominikbrodowski net>, xfs oss sgi com, Christoph Hellwig <hch infradead org>, dm-devel redhat com, josef redhat com
- Subject: Re: [dm-devel] direct-io regression [Was: How to track down abysmal performance ata - raid1 - crypto - vg/lv - xfs]
- Date: Thu, 5 Aug 2010 15:01:38 -0400
On Thu, Aug 05, 2010 at 02:58:37PM -0400, Jeff Moyer wrote:
> Chris Mason <chris mason oracle com> writes:
>
> > But, I'm surprised your drive is doing 8K dio reads at 16MB/s, that
> > seems a little high.
>
> I'm not sure why you think that. We're talking about a plain old SATA
> disk, right? I can get 40-50MB/s on my systems for 8KB O_DIRECT reads.
> What am I missing?
Clearly I'm wrong, his drive is going much faster ;) I expect the
smaller reads to be slower but the drive's internal cache is doing well.
-chris
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