On Fri, Aug 09, 2013 at 10:50:27AM -0400, Vince Weaver wrote: > On Wed, 7 Aug 2013, Arnaldo Carvalho de Melo wrote: > > > From: Jiri Olsa <jo...@redhat.com> > > > > The only way to get the event ID is by reading the event fd, > > followed by parsing the ID value out of the returned data. > > > > While this is ok for current read format used by perf tool, > > it is not ok when we use PERF_FORMAT_GROUP format. > > > > With this format the data are returned for the whole group > > and there's no way to find out what ID belongs to our fd > > (if we are not group leader event). > > I'm a little confused by this. > > If you have an event group (with PERF_FORMAT_GROUP) and you specify > PERF_FORMAT_ID in read_format, then when you read you get the id > values for each sibling event along with their values, right? > > This is how PAPI does things. So I wouldn't say it's impossible to get > the event IDs with PERF_FORMAT_GROUP events. > > Though maybe you're saying it's hard to map sibling fds to id values if > you don't have the list of all fds in an event group in the order they > were added. Which I guess may be true, but I'd think your analysis tool > would have other problems if you didn't have that mapping.
right, the idea behind is not to be dependent on how kernel chains events in the list jirka -- 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/
