- Subject: Re: [Lsf-pc] [LSF/MM TOPIC] a few storage topics
- From: Jeff Moyer <jmoyer@xxxxxxxxxx>
- Date: Tue, 24 Jan 2012 14:11:55 -0500
- Cc: Andreas Dilger <adilger@xxxxxxxxx>, Andrea Arcangeli <aarcange@xxxxxxxxxx>, Jan Kara <jack@xxxxxxx>, "linux-scsi@xxxxxxxxxxxxxxx" <linux-scsi@xxxxxxxxxxxxxxx>, Mike Snitzer <snitzer@xxxxxxxxxx>, "dm-devel@xxxxxxxxxx" <dm-devel@xxxxxxxxxx>, Boaz Harrosh <bharrosh@xxxxxxxxxxx>, "linux-fsdevel@xxxxxxxxxxxxxxx" <linux-fsdevel@xxxxxxxxxxxxxxx>, "lsf-pc@xxxxxxxxxxxxxxxxxxxxxxxxxx" <lsf-pc@xxxxxxxxxxxxxxxxxxxxxxxxxx>, Chris Mason <chris.mason@xxxxxxxxxx>
- In-reply-to: <20120124184054.GA23227@infradead.org> (Christoph Hellwig's message of "Tue, 24 Jan 2012 13:40:54 -0500")
- References: <4F1758D4.9010401@panasas.com> <20120119094637.GA23442@quack.suse.cz> <4F1BFF5F.6000502@panasas.com> <20120123161857.GC28526@quack.suse.cz> <20120123175353.GD30782@redhat.com> <x49r4yq9suf.fsf@segfault.boston.devel.redhat.com> <20120124151504.GQ4387@shiny> <20120124165631.GA8941@infradead.org> <186EA560-1720-4975-AC2F-8C72C4A777A9@dilger.ca> <x49fwf5kmbl.fsf@segfault.boston.devel.redhat.com> <20120124184054.GA23227@infradead.org>
- Reply-to: device-mapper development <dm-devel@xxxxxxxxxx>
- User-agent: Gnus/5.110011 (No Gnus v0.11) Emacs/23.1 (gnu/linux)
Christoph Hellwig <hch@xxxxxxxxxxxxx> writes:
> All three filesystems use the generic mpages code for reads, so they
> all get the same (bad) I/O patterns. Looks like we need to fix this up
> ASAP.
Actually, in discussing this with Vivek, he mentioned that read ahead
might be involved. Sure enough, after bumping read_ahead_kb, 1MB I/Os
are sent down to the storage (for xfs anyway).
Cheers,
Jeff
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