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    SubjectRe: [BUG] Strange 1-second pauses during Resume-from-RAM

    * Jörn Engel <joern@logfs.org> wrote:

    > I do. Went through 10odd runs and annotated the function right below
    > mcount each time. Seems to work now.
    >
    > Trouble is that it doesn't solve my real problem at hand. Something
    > is causing significant delays when writing to logfs. Core logfs code
    > is not running, but may cause whatever other code is running and
    > burning up all the cpu time. Wasting 100ms of "qemu-time" to write a
    > single page happens fairly frequently.
    >
    > With the latency tracer the problem appears to have become worse. Now
    > the loftlockup code triggers quite frequently. Which makes a bit of
    > sense, as the problem is a busy CPU, rather than an idle one.

    well what does the trace say, where do the delays come from? To get a
    quick overview you can make tracing lighter weight by doing:

    echo 0 > /proc/sys/kernel/mcount_enabled
    echo 1 > /proc/sys/kernel/trace_syscalls

    (this turns the latency tracer into a "global strace" kind of tracer)

    Ingo
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