Messages in this thread | | | From | "Liang, Kan" <> | Subject | RE: [PATCH V2 6/8] perf top: add overwrite fall back | Date | Mon, 18 Dec 2017 19:13:06 +0000 |
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> > On 2017/12/7 7:33, kan.liang@intel.com wrote: > > From: Kan Liang <kan.liang@intel.com> > > > > Switch to non-overwrite mode if kernel doesnot support overwrite > > ringbuffer. > > > > It's only effect when overwrite mode is supported. > > No change to current behavior. > > > > Signed-off-by: Kan Liang <kan.liang@intel.com> > > --- > > tools/perf/builtin-top.c | 35 +++++++++++++++++++++++++++++++++++ > > 1 file changed, 35 insertions(+) > > > > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > > index 5e15d27..7c462d6 100644 > > --- a/tools/perf/builtin-top.c > > +++ b/tools/perf/builtin-top.c > > @@ -931,6 +931,27 @@ static int perf_top_overwrite_check(struct > perf_top *top) > > return 0; > > } > > > > +static int perf_top_overwrite_fallback(struct perf_top *top, > > + struct perf_evsel *evsel) > > +{ > > + struct record_opts *opts = &top->record_opts; > > + struct perf_evlist *evlist = top->evlist; > > + struct perf_evsel *counter; > > + > > + if (!opts->overwrite) > > + return 0; > > + > > + /* only fall back when first event fails */ > > + if (evsel != perf_evlist__first(evlist)) > > + return 0; > > + > > + evlist__for_each_entry(evlist, counter) > > + counter->attr.write_backward = false; > > + opts->overwrite = false; > > + ui__warning("fall back to non-overwrite mode\n"); > > + return 1; > > You can check perf_missing_features.write_backward here. Only do the > fallback > when we know the problem is caused by missing of write_backward. >
perf_missing_features is only defined in evsel.c I will add an inline function in evsel.c to do the check.
Thanks, Kan
> > +} > > + > > static int perf_top__start_counters(struct perf_top *top) > > { > > char msg[BUFSIZ]; > > @@ -954,6 +975,20 @@ static int perf_top__start_counters(struct > perf_top *top) > > try_again: > > if (perf_evsel__open(counter, top->evlist->cpus, > > top->evlist->threads) < 0) { > > + > > + /* > > + * Specially handle overwrite fall back. > > + * Because perf top is the only tool which has > > + * overwrite mode by default, support > > + * both overwrite and non-overwrite mode, and > > + * require consistent mode for all events. > > + * > > + * May move it to generic code with more tools > > + * have similar attribute. > > + */ > > + if (perf_top_overwrite_fallback(top, counter)) > > + goto try_again; > > + > > It will unconditionally remove backward bit even if the problem > is caused by other missing feature. > > Thank you.
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