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    SubjectRe: [patch] Real-Time Preemption, -RT-2.6.11-rc3-V0.7.38-01
    On Sat, 2005-02-19 at 15:45 -0500, Lee Revell wrote:
    > On Sat, 2005-02-19 at 10:03 +0100, Ingo Molnar wrote:
    > > * Ingo Molnar <> wrote:
    > >
    > > > > Testing on an all SCSI 1.3Ghz Athlon XP system, I am seeing very long
    > > > > latencies in the journalling code with 2.6.11-rc4-RT-V0.7.39-02.
    > > >
    > > > could you send me the full trace?
    > >
    > > just in case the system in question is still running - could you also do
    > > a 'verbose' trace via:
    > >
    > > echo 1 > /proc/sys/kernel/trace_verbose
    > OK, here is a 2912us verbose latency trace with "data=ordered", gzipped.
    > dbench 32 or 64 is the easiest way to trigger these.
    > I have not tried "data=journal". As previously stated "data=writeback"
    > works perfectly - I ran JACK overnight while stressing the fs and did
    > not get one xrun.

    Any update on this? The problem is still apparent in 2.6.11. It seems
    to be a regression from 2.6.10. And now I've heard 2.6.12-rc1 mentioned
    with no motion on this.

    Here's the trace again in case you missed it:

    The "latency regressions" thread was all sub-millisecond stuff which can
    be ignored IMHO. Still interesting because they are regressions after
    all, but not a real world problem.

    However this one can be several milliseconds. It's a real problem.

    I'd hate to have to ship 2.6.12 with a disclaimer that ext3 with
    "data=ordered" is not suitable for the desktop (as it clearly violates
    the stated desktop responsiveness goal of 1ms).


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