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    SubjectRe: [PATCH 0/11] Per-bdi writeback flusher threads v9
    On Fri, Jun 05, 2009 at 11:14:38PM +0200, Jan Kara wrote:
    > On Fri 05-06-09 21:15:28, Jens Axboe wrote:
    > > On Fri, Jun 05 2009, Frederic Weisbecker wrote:
    > > > The result with noop is even more impressive.
    > > >
    > > > See: http://kernel.org/pub/linux/kernel/people/frederic/dbench-noop.pdf
    > > >
    > > > Also a comparison, noop with pdflush against noop with bdi writeback:
    > > >
    > > > http://kernel.org/pub/linux/kernel/people/frederic/dbench-noop-cmp.pdf
    > >
    > > OK, so things aren't exactly peachy here to begin with. It may not
    > > actually BE an issue, or at least now a new one, but that doesn't mean
    > > that we should not attempt to quantify the impact.
    > What looks interesting is also the overall throughput. With pdflush we
    > get to 2.5 MB/s + 26 MB/s while with per-bdi we get to 2.7 MB/s + 13 MB/s.
    > So per-bdi seems to be *more* fair but throughput suffers a lot (which
    > might be inevitable due to incurred seeks).
    > Frederic, how much does dbench achieve for you just on one partition
    > (test both consecutively if possible) with as many threads as have those
    > two dbench instances together? Thanks.

    Is the graph showing us dbench tput or disk tput? I'm assuming it is
    disk tput, so bdi may just be writing less?

    -chris



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