Messages in this thread | | | Date | Tue, 23 Dec 2014 13:06:33 +0900 | From | Namhyung Kim <> | Subject | Re: [PATCH 7/7] perf tools: Set attr.task bit for a tracking event |
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On Mon, Dec 22, 2014 at 11:49:19AM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, Dec 22, 2014 at 01:44:15PM +0900, Namhyung Kim escreveu: > > The perf_event_attr.task bit is to track task (fork and exit) events > > but it missed to be set by perf_evsel__config(). While it was not a > > problem in practice since setting other bits (comm/mmap) ended up > > being in same result, it'd be good to set it explicitly anyway. > > I didn't understand, so this isn't strictly needed? I.e. what is the > point of the attr->task bit then?
Yes, it's not strictly needed for this case. The attr->task is to track task related events (fork/exit) only but other meta events like comm and mmap[2] also needs the task events. So setting attr->comm and/or attr->mmap causes the kernel emits the task events anyway. So the attr->task is only meaningful when other bits are off but I'd like to set it for completeness.
Thanks, Namhyung
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