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    SubjectRe: new perfmon code base, libpfm, pfmon available
    On Mon, Jun 26, 2006 at 01:33:03PM -0400, Chuck Ebbert wrote:
    > 32-bit works great. Unfortunately, pfmon is far too limited for serious
    > kernel monitoring AFAICT.

    I think "far too limited for serious kernel monitoring" is not a fair
    statement. One can do some very interesting things as I presented
    two years ago at OLS:

    It's just a _very_ complex subsystem and has a steep learning curve
    to do some of the more complex things that one might like.

    > E.g. you can't select edge counting instead
    > of cycle counting. So you can count how many clock cycles were spent
    > with interrupts disabled but you can't count how many times they were
    > disabled.

    At first glance, this example sounds more like a limitation of the HW
    and not the SW.

    > And is someone working on kernel profiling tools that use the perfmon2
    > infrastructure on i386? I'd like to see kernel-based profiling that lets
    > you use something like the existing 'readprofile' to retrieve results. This
    > would be a lot better than the current timer-based profiling.

    Both are useful. I wouldn't say one of necessarily better.
    FWIW, the "CPU_CYCLES" counts from pfmon aren't timer based on ia64.
    AFAIK, the HW counters are sampled to gather those counts.

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      Last update: 2006-06-26 21:33    [W:0.020 / U:9.164 seconds]
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