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    SubjectRe: [PATCH 4/4] Implement semaphore latency tracer
    On 2008-10-22 20:22, Peter Zijlstra wrote:
    > On Wed, 2008-10-22 at 17:48 +0200, Ingo Molnar wrote:
    >
    >> * Török Edwin <edwintorok@gmail.com> wrote:
    >>
    >>
    >>> On 2008-10-22 18:28, Ingo Molnar wrote:
    >>>
    >>>> hm, but the most common synchronization primitive are mutexes - and
    >>>> those are not covered by your patchset.
    >>>>
    >>>>
    >>> Indeed. I've seen a patch from Jason Baron to introduce tracepoints
    >>> for mutexes, but the conclusion was that the tracepoints should be in
    >>> lockstat instead.
    >>>
    >>> And if lockstat is enabled Peter Zijlstra's 'contend with points'
    >>> patch seems to do exactly what I want to.
    >>>
    >>> However I think it would be useful to have (a tracepoints based?)
    >>> latency tracker, which can be enabled/disabled at runtime, and which
    >>> doesn't add any data to the mutex/semaphore structures. My patchset
    >>> was a first attempt towards that, but it seems that such use of
    >>> tracepoints is not welcome at this time?
    >>>
    >>> Please tell me if I should continue working on this, or if I my
    >>> patches are designed totally on the wrong way.
    >>>
    >> i think if you hook into Peter's lockstat APIs that should give us a
    >> pretty good tracer, with no ugliness introduced. That would be rather
    >> interesting. Peter, do you concur?
    >>
    >
    > Yes, I've already suggested this. Use the exact same hooks that
    > lockdep/lockstat use.

    Ok, I'll work on this when I get some time :)
    [hopefully this weekend test the 'contend with points patch', next
    weekend write the new tracepoints]

    Best regards,
    --Edwin
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