Messages in this thread | | | Date | Mon, 24 Jul 2017 14:34:37 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period option showing number of samples |
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Em Sun, Jul 23, 2017 at 08:46:20AM -0700, Andi Kleen escreveu: > On Sun, Jul 23, 2017 at 07:46:05AM +0900, Namhyung Kim wrote: > > Hi Arnaldo and Taeung, > > > > (+ Andi) > > > > On Fri, Jul 21, 2017 at 11:47:48AM -0300, Arnaldo Carvalho de Melo wrote: > > > Em Thu, Jul 20, 2017 at 06:36:55AM +0900, Taeung Song escreveu: > > > > +++ b/tools/perf/builtin-annotate.c > > > > @@ -177,14 +177,12 @@ static int perf_evsel__add_sample(struct perf_evsel *evsel, > > > > */ > > > > process_branch_stack(sample->branch_stack, al, sample); > > > > > > > > - sample->period = 1; > > > > sample->weight = 1; > > > > - > > > > he = hists__add_entry(hists, al, NULL, NULL, NULL, sample, true); > > > > if (he == NULL) > > > > return -ENOMEM; > > > > > > I split the hunk above into a separate patch, as a fix, Namhyung, can > > > you take a look at why need to unconditionally overwrite what is in > > > sample->weight as well? > > > > > > Looks fishy as it may come with a value from the kernel, parsed in > > > perf_evsel__parse_sample(), when PERF_SAMPLE_WEIGHT is in > > > perf_event_attr->sample_type. > > > > > > Is it that the hists code needs a sane value when PERF_SAMPLE_WEIGHT > > > isn't requested in sample_type? > > > > It was Andi added that code originally (05484298cbfe). IIUC the > > weight is only meaningful for some CPUs with Intel TSX and he used a > > dummy value. > > It's used for more than TSX. e.g. perf mem uses it for memory latencies. > > > AFAIK the hists code doesn't care of it unless weight sort key is used > > (for report). As it's not used by annotate code, I think it'd be > > better leaving it as is (like period). > > Right, it's needed when weight is specified as a sort key. But we need > a fallback in case the user specified weight in perf report, but > didn't enable it for perf record.
Humm, shouldn't we fail in that case? I.e. user asks for per-sample property not collected at 'perf record' time?
That or the weight sort order handler should see that perf_sample->weight is zero and assume it wasn't collected then turn it into a 1? Or just look at evsel->attr.sample_type & PERF_SAMPLE_WEIGHT?
- Arnaldo
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