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    SubjectRe: [patch 00/52] vfs scalability patches updated
    On Wed, Jun 30, 2010 at 10:40:49PM +1000, Nick Piggin wrote:
    > But actually it's not all for scalability. I have some follow on patches
    > (that require RCU inodes, among other things) that actually improve
    > single threaded performance significnatly. git diff workload IIRC was
    > several % improved from speeding up stat(2).

    I rewrote the store-free path walk patch that goes on top of this
    patchset (it's now much cleaner and more optimised, I'll post a patch
    soonish). It is quicker than I remembered.

    A single thread running stat(2) in a loop on a file "./file" has the
    following cost (on an 2s8c Barcelona):

    2.6.35-rc3 595 ns/op
    patched 336 ns/op

    stat(2) takes 56% the time with patches. It's something like 13 fewer
    atomic operations per syscall.

    What's that good for? A single threaded, cached `git diff` on the linux
    kernel tree takes just 81% of the time after the vfs patches (0.27s vs

     \ /
      Last update: 2010-07-01 19:25    [W:0.020 / U:39.408 seconds]
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