Re: [RFC PATCH v2 1/2] perf tools: Set evsel->system_wide field for global system wide recording

[Wangnan (F)]

On 2015/10/26 20:24, Adrian Hunter wrote:
> On 26/10/15 13:41, Wang Nan wrote:
> > evsel->system_wide is introduced by commit bf8e8f4b832972c76d64ab2e2837
> > (perf evlist: Add 'system_wide' option), which is used for mixing evsels
> > that aren't system-wide with ones that are [1]. However, for global
> > system wide recording (perf record -a ...), evsel->system_wide is set
> > to false, which is confusion.
> >
> > This patch set evsel->system_wide to true if the target.system_wide is
> > set, which makes evsel->system_wide a reliable way to describe whether
> > itself is system_wide or not.
> >
> > [1] http://lkml.kernel.org/r/562DF19B.2080608@xxxxxxxxx
> >
> > Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
> > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
> > Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
> > Cc: Li Zefan <lizefan@xxxxxxxxxx>
> > Cc: pi3orama@xxxxxxx
> > Link: http://lkml.kernel.org/n/ebpf-qm3gtwidc1o5ktjd9tgjex25@xxxxxxxxxxxxxx
> > ---
> >   tools/perf/util/evsel.c | 1 +
> >   1 file changed, 1 insertion(+)
> >
> > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> > index 3ac4ee9c..36ecf0e 100644
> > --- a/tools/perf/util/evsel.c
> > +++ b/tools/perf/util/evsel.c
> > @@ -734,6 +734,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts)
> >   	int track = evsel->tracking;
> >   	bool per_cpu = opts->target.default_per_cpu && !opts->target.per_thread;
> >   
> > +	evsel->system_wide = opts->target.system_wide;
> Well that breaks the way evsel->system_wide is used i.e. it is a parameter
> to the evsel and here you just overwrote it.

Currently the only user of evsel->system_wide is IPT:

auxtrace_record__options -> intel_pt_recording_options

and it only set it to true.

So I think changing to this should make it safe:

evsel->system_wide = (evsel->system_wide || opt->target.system_wide);

Thought?

If we want to add further config terms we can put it to 
apply_config_terms(),
where we can implement something like:

 # perf record -e cycles/system-wide/ -e instruction/no-system-wide/ ...

But currently I don't have such requirement.

Thank you.

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