Messages in this thread | | | Date | Fri, 24 Apr 2015 21:56:06 +0800 | From | Yunlong Song <> | Subject | Re: [Question] How does perf still record the stack of a specified pid even when that process is interrupted and CPU is scheduled to other process |
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On 2015/4/24 21:49, David Ahern wrote: > On 4/24/15 7:31 AM, Yunlong Song wrote: >> [Profiling Problem] >> >> Although perf can record the events (with call stack) of a specified pid, e.g. using >> "perf record -g iozone -s 262144 -r 64 -i 0 -i 2". But we find iozone is interrupted > > That command tells perf to *only* collect data for iozone. This command: > > perf record -g -a -- iozone .... > > tells perf to collect samples system wide as long as the iozone process is alive. > > >
But we only want the records of iozone rather than the overall system, since other process will interfere the targeted I/O stack of the specific 1% case, and we cannot figure out the "clean" specific stack which takes up 60% time.
-- Thanks, Yunlong Song
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