[xfs-masters] [Bug 15967] XFS is insanely slow at deleting files on a highly fragmented FS

[bugzilla-daemon at bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=15967


Dave Chinner <david at fromorbit.com> changed:

           What    |Removed                     |Added
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                 CC|                            |david at fromorbit.com
         AssignedTo|xfs-masters at oss.sgi.com     |david at fromorbit.com




--- Comment #3 from Dave Chinner <david at fromorbit.com>  2010-05-14 01:37:20 ---

Artem, if you had done any reading at all, you would have found out all about
the options XFS provides for preventing fragmentation in your use case. If
you've got a simple problem like this, ask on the xfs mailing list before
raising a bug. Workarounds:

1. speed up unlink: mount option "logbsize=262144"
2. prevent fragmentation with large files written simultaneously: mount option
"allocsize=64m"
3. preallocation should be done by posix_fallocate() or ioctl(XFS_IOC_RESVSP)

That being said, there is a known bug in 2.6.33 (at least, not sure when it was
introduced) in the generic code to help prevent _ext4_ fragmentation in exactly
this workload. Unintentional bugs in that change have caused regressions in
_XFS_ writeback that cause excessive fragmentation but fixes are still in
progress. The above tunings will work around the fragmentation problems that
the bug causes in the mean time.

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