Em Fri, Jan 09, 2015 at 11:26:54AM -0500, Vince Weaver escreveu: > > On Fri, 9 Jan 2015, Peter Zijlstra wrote: > > > So is this worth fixing seeing as apparently no one uses this feature? > > > > I think there's a fair argument for removing it, Ingo, Acme? > > could the functionality be replaced with a subsequent call to > ioctl(PERF_EVENT_IOC_SET_OUTPUT) > ?
That is the only thing tools/perf uses: [acme@zoo linux]$ find tools/perf -name "*.[chly]" | xargs grep PERF_EVENT_IOC_SET_OUTPUT tools/perf/util/evlist.h: * @refcnt - e.g. code using PERF_EVENT_IOC_SET_OUTPUT to share this tools/perf/util/evlist.c: if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0) tools/perf/tests/perf-record.c: * (using ioctl(PERF_EVENT_IOC_SET_OUTPUT)). [acme@zoo linux]$ find tools/perf -name "*.[chly]" | xargs grep PERF_FLAG_FD_OUTPUT [acme@zoo linux]$ > Although I suppose there's a possibility for losing a small amount of data > or some other reason that PERF_FLAG_FD_OUTPUT was introduced in the first > place. Humm, IIRC tools/perf starts with the event disabled and then asks for enable_on_exec when starting workloads but yes, when you're attaching to something that is already running you'd take a bit longer to start getting samples. > In addition, if we remove PERF_FLAG_FD_OUTPUT would there then be any > reason to keep PERF_FLAG_FD_NO_GROUP around? > > Vince -- 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/
