Re: [BUG] Strange 1-second pauses during Resume-from-RAM
From: Ingo Molnar
Date: Thu Nov 15 2007 - 14:35:35 EST
* Mark Lord <lkml@xxxxxx> 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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