On Mon, Jul 13, 2015 at 07:01:51PM +0000, Liang, Kan wrote: > > On Wed, Jul 08, 2015 at 04:44:55AM -0400, kan.li...@intel.com wrote: > > > From: Kan Liang <kan.li...@intel.com> > > > > > > When multiple events are sampled it may not be needed to collect fine > > > grained time stamps on all events. The sample sites are usually nearby. > > > It's enough to have time stamps on the regular reference events. > > > This patchkit adds the ability to turn off time stamps per event. This > > > in term can reduce sampling overhead and the size of the perf.data. > > > > So this patch makes the PERF_SAMPLE_TIME bit set or not independently, > > right? But AFAIK we sometimes just use first evsel for checking > > sample_type value, especially for evlist->id_pos. I'm not sure it'll work > > for > > all cases of mixed time/notime events.. > > > > If the sample_type is different, IDENTIFIER will be set to make sure id is in > a fixed position. So we don't need to worry about evlist->id_pos here. > > I think the only unsupported case should be that the kernel doesn't > support IDENTIFIER. If so, under my test, perf record will print warning > " failed to process type". Perf report will also print warning > " non matching sample_type". So the user can switch back to full time > support.
Ah, ok then. > If you think the warning is not good enough, we can show specific > warning and error out when non IDENTIFIER support is detected. Well, I think it's good enough. :) However, perf_evlist__id_hdr_size() seems to be affected also. Are you sure it's okay too? Thanks, Namhyung -- 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/
