Re: [PATCH v2 1/2] perf evlist: Ensure grouped events with same cpu map

Jin, Yao
2020-05-27T03:20:48Z

Hi Jiri,

On 5/26/2020 7:51 PM, Jiri Olsa wrote:
> On Mon, May 25, 2020 at 02:55:58PM +0800, Jin Yao wrote:
>
> SNIP
>
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index 2a9de6491700..1161cffc0688 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -1704,3 +1704,52 @@ struct evsel *perf_evlist__reset_weak_group(struct evlist *evsel_list,
>> }
>> return leader;
>> }
>> +
>> +static bool cpus_map_matched(struct evsel *prev, struct evsel *evsel)
>> +{
>> + if (evsel->core.cpus->nr != prev->core.cpus->nr)
>> + return false;
>> +
>> + for (int i = 0; i < evsel->core.cpus->nr; i++) {
>> + if (evsel->core.cpus->map[i] != prev->core.cpus->map[i])
>> + return false;
>> + }
>> +
>> + return true;
>> +}
>> +
>> +bool evlist__cpus_map_matched(struct evlist *evlist)
>> +{
>> + struct evsel *prev = evlist__first(evlist), *evsel = prev;
>> + int nr_members = prev->core.nr_members;
>> +
>> + evlist__for_each_entry_continue(evlist, evsel) {
>> + if (nr_members <= 1) {
>> + prev = evsel;
>> + nr_members = evsel->core.nr_members;
>> + continue;
>> + }
>> +
>> + nr_members--;
>> +
>> + if (!cpus_map_matched(prev, evsel))
>> + return false;
>> +
>> + prev = evsel;
>> + }
>> +
>> + return true;
>> +}
>> +
>> +void evlist__force_disable_group(struct evlist *evlist)
>> +{
>> + struct evsel *evsel;
>> +
>> + pr_warning("WARNING: event cpu maps are not fully matched, "
>> + "stop event grouping\n");
>> +
>> + evlist__for_each_entry(evlist, evsel) {
>> + evsel->leader = evsel;
>> + evsel->core.nr_members = 0;
>> + }
>> +}
>
> I think this is too much, we need to disable only groups with not
> matching cpus, not all of them, how about something like this
>

Yes, that's too much.

>
> struct evsel *pos;
>
> evlist__for_each_entry(evlist, evsel) {
> if (evsel->leader == evsel)
> continue;
> if (!cpus_map_matched(evsel->leader, evsel))
> continue;
>
> pr_warn("Disabling group...
>
> for_each_group_member(pos, evsel->leader) {
> pos->leader = pos;
> evsel->core.nr_members = 0;
> }
> }
>
> jirka
>

Hmm, change "!cpus_map_matched()" to "cpus_map_matched()"? and use for_each_group_evsel() to replace
for_each_group_member()?

How about something like following?

void evlist__check_cpu_maps(struct evlist *evlist)
{
struct evsel *evsel, *pos;

evlist__for_each_entry(evlist, evsel) {
if (evsel->leader == evsel)
continue;

if (cpu_maps_matched(evsel->leader, evsel))
continue;

pr_warning("WARNING: event cpu maps are not fully matched, "
"disable group\n");

for_each_group_evsel(pos, evsel->leader) {
pos->leader = pos;
pos->core.nr_members = 0;
}

/*
* For core & uncore mixed event group, for example,
* '{cycles,unc_cbo_cache_lookup.any_i}',
* In evlist:
* cycles,
* unc_cbo_cache_lookup.any_i,
* unc_cbo_cache_lookup.any_i,
* unc_cbo_cache_lookup.any_i,
* unc_cbo_cache_lookup.any_i,
*
* cycles is leader and all unc_cbo_cache_lookup.any_i
* point to this leader. But for_each_group_evsel can't
* iterate all members from cycles. It only iterates
* cycles and one unc_cbo_cache_lookup.any_i. So we
* set extra evsel here.
*/
evsel->leader = evsel;
evsel->core.nr_members = 0;
}
}

Thanks
Jin Yao