On Tue, Sep 9, 2014 at 5:03 PM, Andi Kleen <a...@firstfloor.org> wrote: > From: Andi Kleen <a...@linux.intel.com> > > It's currently difficult to filter out perf itself using a filter. > This can give cascading effects during IO tracing when the IO > perf does itself causes more trace output. > > The best way to filter is to use the pid. But it's difficult to get the pid > of perf without using hacks. > > Add a PERF_PID meta variable to the perf filter that contains the current pid. > > With this patch the following works > > % perf record -e syscalls:sys_enter_write -a --filter 'common_pid != > PERF_PID' ... > > This won't work for more complex perf pipe lines with multiple processes, > but at least solves the problem nicely for a single perf.
Thank you, this will be handy. I tested it and it works. It will mean I can avoid hacks like this: https://github.com/brendangregg/perf-tools/blob/d30e8a1a9f136d532ba78c6d48aedb99dc316be9/syscount#L144 I think it's unrelated to this patch, but the very next test I tried didn't work as expected: # perf record -e 'syscalls:sys_enter_*' --filter 'common_pid != PERF_PID' -a sleep 5 It only filters the last event from the wildcard expansion, leaving write() unfiltered. Looks like it's because parse_filter() is only setting the filter for perf_evlist__last(), instead of doing an evlist__for_each(). How best to deal with this can be addressed in a separate patch later. Brendan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/