Messages in this thread | | | Date | Tue, 12 May 2015 14:43:44 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH V9 8/8] perf tools: handle PERF_RECORD_LOST_SAMPLES |
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On Mon, May 11, 2015 at 06:27:58PM -0300, Arnaldo Carvalho de Melo wrote: > Em Mon, May 11, 2015 at 08:40:56PM +0000, Liang, Kan escreveu: > > > Em Sun, May 10, 2015 at 03:13:15PM -0400, Kan Liang escreveu: > > > > $ perf record -e '{cycles:p,instructions:p}' -c 20003 --no-time > > > > ~/tchain ~/tchain [perf record: Woken up 148 times to write data] > > > > [perf record: Captured and wrote 36.922 MB perf.data (1206322 > > > > samples)] > > > > > $ perf report -D | tail > > > > SAMPLE events: 120243 > > > > MMAP2 events: 5 > > > > LOST_SAMPLES events: 24 > > > > FINISHED_ROUND events: 15 > > > > cycles:p stats: > > > > TOTAL events: 59348 > > > > SAMPLE events: 59348 > > > > instructions:p stats: > > > > TOTAL events: 60895 > > > > SAMPLE events: 60895 > > > > The example doesn't show which of cycles:p or instructions:p got lost, isn't > > > that possible? Guess not from the patch, but should, no? I.e. what is > > > PERF_SAMPLE_ID for then? > > > Yes, it's possible to know the lost samples number for cycles:p or > > instructions:p. But I didn't implement it in the summary of perf report -D. > > I think a total lost_samples number is enough for user. What they really > > care about should be the total samples drop rate. > > (If they really want to know the number of which event got lost, they can > > search LOST_SAMPLES in perf report -D. sample->id is dumped with lost > > number.) > > I disagree, since the support is there, we need to have it in > hists->events_stats[PERF_RECORD_LOST_SAMPLES]. > > But that can be done in a follow up patch.
Agreed, it would be good to know of which event the samples got lost.
> It just came quickly to my attention because of all the discussion about > where to store something (PERF_SAMPLE_ID via sample_type + sample_id_all) > that doesn't get used in the patch that introduces it :-) > > I'll try to test this all tomorrow and will try to do the needed wiring > to hists_evsel->hists->events_stats. > > All working I can push this all via my perf/core event, if PeterZ > agrees and is ok with the kernel specific bits.
I would like to carry these as there some conflicts with other patches I have.
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