On Thu, Apr 30, 2020 at 09:54:18AM +0100, John Garry wrote:
> On 30/04/2020 09:45, Jiri Olsa wrote:
> > On Thu, Apr 30, 2020 at 08:36:18AM +0800, Jin Yao wrote:
> > > A big uncore event group is split into multiple small groups which
> > > only include the uncore events from the same PMU. This has been
> > > supported in the commit 3cdc5c2cb924a ("perf parse-events: Handle
> > > uncore event aliases in small groups properly").
> > >
> > > If the event's PMU name starts to repeat, it must be a new event.
> > > That can be used to distinguish the leader from other members.
> > > But now it only compares the pointer of pmu_name
> > > (leader->pmu_name == evsel->pmu_name).
> > >
> > > If we use "perf stat -M LLC_MISSES.PCIE_WRITE -a" on cascadelakex,
> > > the event list is:
> > >
> > > evsel->name evsel->pmu_name
> > > ---------------------------------------------------------------
> > > unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_4 (as leader)
> > > unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_2
> > > unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_0
> > > unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_5
> > > unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_3
> > > unc_iio_data_req_of_cpu.mem_write.part0 uncore_iio_1
> > > unc_iio_data_req_of_cpu.mem_write.part1 uncore_iio_4
> > > ......
> > >
> > > For the event "unc_iio_data_req_of_cpu.mem_write.part1" with
> > > "uncore_iio_4", it should be the event from PMU "uncore_iio_4".
> > > It's not a new leader for this PMU.
> > >
> > > But if we use "(leader->pmu_name == evsel->pmu_name)", the check
> > > would be failed and the event is stored to leaders[] as a new
> > > PMU leader.
> > >
> > > So this patch uses strcmp to compare the PMU name between events.
> > >
> > > Fixes: 3cdc5c2cb924a ("perf parse-events: Handle uncore event aliases in
> > > small groups properly")
> > > Signed-off-by: Jin Yao <[email protected]>
> >
> > looks good, any chance we could have automated test
> > for this uncore leader setup logic? like maybe the way
> > John did the pmu-events tests? like test will trigger
> > only when there's the pmu/events in the system
> >
> > Acked-by: Jiri Olsa <[email protected]>
> >
> > thanks,
> > jirka
>
> Hi jirka,
>
> JFYI, this is effectively the same patch as I mentioned to you, which was a
> fix for the same WARN:
>
> https://lore.kernel.org/linux-arm-kernel/[email protected]/
>
> but I found that it "fixed" d4953f7ef1a2 ("perf parse-events: Fix 3 use
> after frees found with clang ASANutil/parse-events.c"), based on bisect
> breakage
hum right.. sorry I did not recalled that, there's
also the warn removal in here, could you guys also
plz sync on the fixes clauses?
thanks,
jirka
>
> cheers
>
> >
> >
> > > ---
> > > tools/perf/util/parse-events.c | 5 ++---
> > > 1 file changed, 2 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/tools/perf/util/parse-events.c
> > > b/tools/perf/util/parse-events.c
> > > index 10107747b361..786eddb6a097 100644
> > > --- a/tools/perf/util/parse-events.c
> > > +++ b/tools/perf/util/parse-events.c
> > > @@ -1629,12 +1629,11 @@ parse_events__set_leader_for_uncore_aliase(char
> > > *name, struct list_head *list,
> > > * event. That can be used to distinguish the leader
> > > from
> > > * other members, even they have the same event name.
> > > */
> > > - if ((leader != evsel) && (leader->pmu_name == evsel->pmu_name))
> > > {
> > > + if ((leader != evsel) &&
> > > + !strcmp(leader->pmu_name, evsel->pmu_name)) {
> > > is_leader = false;
> > > continue;
> > > }
> > > - /* The name is always alias name */
> > > - WARN_ON(strcmp(leader->name, evsel->name));
> > > /* Store the leader event for each PMU */
> > > leaders[nr_pmu++] = (uintptr_t) evsel;
> > > --
> > > 2.17.1
> > >
> >
> > .
> >
>
