Messages in this thread | | | From | Wim Heirman <> | Date | Sat, 14 May 2011 20:52:57 +0200 | Subject | Re: perf-stat per thread results |
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2011/5/14 David Ahern <dsahern@gmail.com>: > On 05/14/11 06:49, Wim Heirman wrote: >>> Hmm.... my mileage varies using latest kernel >>> (446cc6345d3de6571bdd0840f48aca441488a28d) >>> >>> $ /tmp/build-perf/perf record --stat -fo /tmp/perf.data -p $(pidof rsyslogd) >>> ^C[ perf record: Woken up 1 times to write data ] >>> [ perf record: Captured and wrote 0.007 MB /tmp/perf.data (~308 samples) ] >>> >>> $ /tmp/build-perf/perf report -T -i /tmp/perf.data >>> # Events: 6 cycles >>> # >>> # Overhead Command Shared Object Symbol >>> # ........ ........ ................. .......................... >>> # >>> 97.61% rsyslogd libc-2.13.so [.] __libc_disable_asynccancel >>> 2.39% rsyslogd [kernel.kallsyms] [k] native_write_msr_safe >>> >>> >>> # >>> # (For a higher level overview, try: perf report --sort comm,dso) >>> # >>> # PID TID >>> >>> >>> ie., I do not get the counter values. Specifying the counter with -e >>> (e.g., -e branch-misses) does not help -- still no counter output. >> >> Is rsyslogd multithreaded? (Or at least, do the non-main threads >> execute any work during your perf-record measurement) If not, then >> what you see is consistent with what I'm getting, i.e. everything but >> the main thread is reported. > > It is multithreaded, but my point is that I do not get counter output at > the end -- the PID/TID table is empty. I do not get counters for single > threaded processes nor for commands run by perf record -- e.g., > /tmp/build-perf/perf record --stat -e instructions -fo /tmp/perf.data -- > sleep 1
My guess was that none of the threads got scheduled while you did your perf-record run (rsyslogd usually isn't exactly very CPU intensive). And the main thread isn't ever reported, at least that's the bug I'm seeing. Can you try with a compute-intensive, multi-threaded program?
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