Filesystem writes on RAID5 too slow
Christoph Hellwig
hch at infradead.org
Tue Dec 10 13:18:03 CST 2013
> xfs: align initial file allocations correctly.
>
> From: Dave Chinner <dchinner at redhat.com>
>
> The function xfs_bmap_isaeof() is used to indicate that an
> allocation is occurring at or past the end of file, and as such
> should be aligned to the underlying storage geometry if possible.
>
> Commit 27a3f8f ("xfs: introduce xfs_bmap_last_extent") changed the
> behaviour of this function for empty files - it turned off
> allocation alignment for this case accidentally. Hence large initial
> allocations from direct IO are not getting correctly aligned to the
> underlying geometry, and that is cause write performance to drop in
> alignment sensitive configurations.
>
> Fix it by considering allocation into empty files as requiring
> aligned allocation again.
Seems like this one didn't get picked up yet?
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