Em Tue, May 11, 2010 at 04:04:17PM +0200, Stephane Eranian escreveu: > I am confused by the inheritance cmd line option of perf record:
> usage: perf record [<options>] [<command>] > or: perf record [<options>] -- <command> [<options>] > -p, --pid <n> record events on existing process id > -t, --tid <n> record events on existing thread id > -a, --all-cpus system-wide collection from all CPUs > -C, --profile_cpu <n> CPU to profile on > -i, --inherit child tasks inherit counters > This leads to believe that by default inheritance in children is off. > However, builtin-record.c says: > static bool inherit = true; > If that's the case, what's the point of the -i option? Humm, since for -C and -a using -i doesn't make sense, I guess it should be off by default and only be auto-activated if we don't specify any option, i.e. when using it like: perf record ./hackbench What do you think? > Another side effect of inheritance is that in per-thread mode, perf > creates as many "sessions" as you have CPUs. So on a 16-way processor, > sampling on cycles, perf creates 16 events and 16 x 2-page sampling > buffers. That's a lot of resources consumed if I am just interested in > monitoring a single-threaded workload. > Am I missing something here? I don't think so, but maybe I'm missing too :-) - Arnaldo ------------------------------------------------------------------------------ _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
