Messages in this thread | | | Date | Sat, 21 Jul 2012 19:16:11 +0200 | Subject | Re: [Question] perf header: Why the HEADER_EVENT_DESC is needed? | From | Stephane Eranian <> |
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On Sat, Jul 21, 2012 at 1:11 PM, Namhyung Kim <namhyung@kernel.org> wrote: > Hi Stephane, > > I wonder why we need to save the event descriptions in the feature area > of file header. Since the perf_event_attr, its ids and the event name > are already saved in the header, it seems a duplicate work to do that. > For printing the information, we might reuse those info or evlist > directly IMHO. > > Am I missing something?
Unfortunately, I think you are.
There event names are not saved in header.c except indirectly by write_cmdline. But more importantly, event_desc makes it possible to connect an event name as passed on the cmdline with the corresponding attr struct.
Furthermore, it is also present in pipe mode, with the patch I posted months ago.
Finally, you cannot arbitrarily remove features like this. We do have tools that do rely on the presence of EVENT_DESC.
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