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    SubjectRe: [patch 00/52] vfs scalability patches updated
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    On Wed, 2010-06-30 at 21:30 +1000, Dave Chinner wrote:
    > Sure, but I have to question how much of this is actually necessary?
    > A lot of it looks like scalability for scalabilities sake, not
    > because there is a demonstrated need...

    Well, we've repeatedly run into problems with contention on the
    dcache_lock as well as the inode_lock; changes that improve those paths
    are extremely interesting to us. I've also seen numbers from systems
    with large (i.e. 32 to 64) numbers of cores that clearly show serious
    problems in this area.

    Further, while this seems like a bunch of patches, a close look shows
    that it basically just pushes the dcache and inode locks down as far as
    possible, making other improvements (such as removal of a few atomics
    and no longer batching inode reclaims, among other things) based on that
    work. I would be hard-pressed to find much to cherry-pick from this
    patch set.

    One interesting thing might be to do a set of performance tests for
    kernels with increasingly more of the patchset, just to see the effect
    of the earlier patches against a vanilla kernel and to measure the
    cumulative effect of the later patches. (I'm not volunteering, however:
    ENOTIME.)
    --
    Frank Mayhar <fmayhar@google.com>
    Google, Inc.



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