Messages in this thread | | | Date | Thu, 29 Sep 2011 23:21:34 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf tools: Exit recording if events have non matching sample type |
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Em Thu, Sep 29, 2011 at 06:58:20PM -0600, David Ahern escreveu: > On 09/29/2011 06:40 PM, Arnaldo Carvalho de Melo wrote: > > This comes from time to time: > > > > http://us.generation-nt.com/answer/bug-perf-event-sampling-buffer-format-cannot-handle-multi-event-sampling-help-202985832.html > > > > The whole point of sample_type is to ask for just what is needed for > > some specific event so that we reduce the per sample footprint. > > > > So we allow for multiple types of events to be on the same stream, but > > not for them to have just what each need, its a limitation, one that we > > can solve. I see no reason not to solve it :-) > > > > The evsel/evlist classes were designed to abstract away such details, > > i.e. perf_evlist__mmap should notice different sample_types and sort > > this out transparently. > > > > And then perf_evlist__mmap_read(evlist, idx), evlist->nr_mmaps should be > > enough to process the events :-) > > > > - Arnaldo > > An ABI change fixes the root cause of the current problem -- put an id > in perf_event_header. The id maps to the evsel which has the > sample_type. Right now you have to parse the sample to get the id to get > the evsel.
This id is not always needed, so it shouldn't go to perf_event_header. Peter, can you comment here? ;-)
- Arnaldo
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