On Fri, Aug 22, 2014 at 03:05:13PM +0200, Jiri Olsa wrote: > hi, > Jen-Cheng(Tommy) Huang reported the leader sampling not working > on children processes: > http://www.mail-archive.com/[email protected]/msg01644.html > > The leader sampling (example below) lets the group leader event (cycles) > do the sampling and reads the rest of the group (cache-misses) via > PERF_FORMAT_GROUP format. > > Example: > $ perf record -e '{cycles,cache-misses}:S' <workload> > $ perf report --group > > The perf report --group allows to see all events group > data in single view. > > The reason for leader sampling being switched off for inherited > events, is that the kernel does no allow PERF_FORMAT_GROUP format > on inherited events (which is used by leader sampling). > > I switched on the PERF_FORMAT_GROUP format for inherited events > with few other fixies in patches: > perf: Deny optimized switch for events read by PERF_SAMPLE_READ > perf: Allow PERF_FORMAT_GROUP format on inherited events > > And I fixed perf tool code to be able to process data from > children processes. > > Anyway, I might have missed some other reason why this was > never switched on in kernel, so sending this as RFC.
Also reachable in here: git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git perf/core_format_group jirka -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
