Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1694968

Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period option showing number of samples

Show all headers | View raw

Em Mon, Jul 24, 2017 at 10:46:38AM -0700, Andi Kleen escreveu:
> On Mon, Jul 24, 2017 at 02:34:37PM -0300, Arnaldo Carvalho de Melo wrote:
> > 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?
> 
> Could fail, but it's essentially a no-op
> > 
> > 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?
> 
> Either 0 or 1 works, it just always needs to be the same value.

Well, perf_evsel__parse_sample() is where that struct
perf_sample->weight is set, and it sets the whole struct to zero, then
goes on parsing using evsel->attr.sample_type to decide what to set, so
I think I can just nuke that setting to one, thanks.

- Arnaldo

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v3 3/9] perf annotate: Fix wrong --show-total-period option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-19 23:40 +0200
  Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-20 21:20 +0200
    Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-21 11:50 +0200
      Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-21 13:30 +0200
        Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-24 04:00 +0200
          Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-24 19:40 +0200
            Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-24 23:30 +0200
              Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-25 16:50 +0200
                Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-25 18:00 +0200
                Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-25 18:20 +0200
                Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-26 14:00 +0200
                Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-26 22:20 +0200
                Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Taeung Song <treeze.taeung@gmail.com> - 2017-07-27 17:20 +0200
              [tip:perf/core] perf annotate stdio: Fix column header when using  --show-total-period tip-bot for Taeung Song <tipbot@zytor.com> - 2017-07-26 19:30 +0200
  Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-21 17:00 +0200
    Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Namhyung Kim <namhyung@kernel.org> - 2017-07-23 00:50 +0200
      Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Andi Kleen <andi@firstfloor.org> - 2017-07-23 17:50 +0200
        Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-24 19:40 +0200
          Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Andi Kleen <andi@firstfloor.org> - 2017-07-24 19:50 +0200
            Re: [PATCH v3 3/9] perf annotate: Fix wrong --show-total-period  option showing number of samples Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-07-24 20:10 +0200
  [tip:perf/core] perf annotate: Store the sample period in each  histogram bucket tip-bot for Taeung Song <tipbot@zytor.com> - 2017-07-26 19:30 +0200
  [tip:perf/core] perf annotate: Do not overwrite sample->period tip-bot for Taeung Song <tipbot@zytor.com> - 2017-07-26 19:30 +0200
  [tip:perf/core] perf hists: Pass perf_sample to  __symbol__inc_addr_samples() tip-bot for Taeung Song <tipbot@zytor.com> - 2017-07-26 19:30 +0200

csiph-web