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    SubjectRe: [PATCH 00/23] per device dirty throttling -v8

    Ingo Molnar <mingo <at>> writes:
    > * Linus Torvalds <torvalds <at>> wrote:
    > > On Fri, 3 Aug 2007, Peter Zijlstra wrote:
    > > >
    > > > These patches aim to improve balance_dirty_pages() and directly address
    > > > three issues:
    > > > 1) inter device starvation
    > > > 2) stacked device deadlocks
    > > > 3) inter process starvation
    > >
    > > Ok, the patches certainly look pretty enough, and you fixed the only
    > > thing I complained about last time (naming), so as far as I'm
    > > concerned it's now just a matter of whether it *works* or not. I guess
    > > being in -mm will help somewhat, but it would be good to have people
    > > with several disks etc actively test this out.
    > There are positive reports in the never-ending "my system crawls like an
    > XT when copying large files" bugzilla entry:
    >[ snipped part of the bug report ]
    > so the whole problem area seems to be a "perfect storm" created by a
    > combination of TCQ, IO scheduling and VM dirty handling weaknesses. Per
    > device dirty throttling is a good step forward and it makes a very
    > visible positive difference.

    Foreword: I'm the OP of bug #7372.

    I just want to say/add that:
    1) I'm running the per-bdi patch since about 30 days on a master mysql server
    under somewhat mild load without any adverse effect I could notice.

    2) I _still_ don't get the "performances" of 2.6.17, but since that's the
    better combination I could get, I think there is IMHO progress in the right
    direction (to be compared to no progress since 2.6.18, that's better :-)).

    To be honest, a vanilla 2.6.17 not tuned at all (ie vfs_cache_pressure and other
    knobs in /proc/sys/vm like swappiness and dirty_*) is still better than any
    other upcoming kernel I tested. Thus I still think 2.6.18 added a big regression
    (which unfortunately I couldn't find).
    Read the full bug report for any background information if needed.

    Unfortunately it isn't practical to git-bisect my issue as the server is a
    production server that can't be rebooted/stopped whenever I want (and since I
    found workarounds of the issue...).

    Thanks for showing interest in this issue.

    Please CC: me on any answers as I'm not subscribed to the list.

    Brice Figureau

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      Last update: 2007-08-05 19:25    [W:0.022 / U:59.832 seconds]
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