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

    * Mark Lord <lkml@rtr.ca> wrote:

    >> Can you try nohz=off highres=off? Strange stuff is happening with
    >> nohz.
    >
    > (added Ingo to CC: list: maybe this is some weird interaction with CFS
    > and jiffies being reset to 0 on resume ??)

    hm, CFS should have no impact here. To see what's happening you could
    try to use the latency tracer of the -rt patch and do a cross-resume
    trace.

    pick up the latest latency tracer patch from:

    http://redhat.com/~mingo/private/latency-tracer-v2.6.24-rc2-git5-combo.patch

    apply it and enable CONFIG_FUNCTION_TRACING, then pick up trace-cmd.c:

    http://redhat.com/~mingo/private/trace-cmd.c

    and do something like:

    ./trace-cmd pm-suspend > trace.txt

    or:

    ./trace-cmd /bin/bash -c "echo ram > /sys/power/state" > trace.txt

    this should trigger suspend - then you should do the resume. If
    everything goes well then trace.txt should contain a pretty large trace
    of all the stuff we do during a suspend+resume.

    and wait for such a pause and send us the resulting trace.txt.

    if it's an SMP box then first do:

    echo 1 > /proc/sys/kernel/trace_all_cpus

    to get a global trace. Let me know if something doesnt work with this
    scheme.

    Ingo
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