Re: [PATCH] perf parse-events: Use strcmp to compare the PMU name
From: Jin, Yao
Date: Thu Apr 30 2020 - 09:38:47 EST
Hi John, Jiri,
On 4/30/2020 7:48 PM, John Garry wrote:
On 30/04/2020 12:15, Jiri Olsa wrote:
+
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->nameÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂÂ evsel->pmu_name
---------------------------------------------------------------
unc_iio_data_req_of_cpu.mem_write.part0ÂÂÂÂÂÂÂ uncore_iio_4 (as leader)
unc_iio_data_req_of_cpu.mem_write.part0ÂÂÂÂÂÂÂ uncore_iio_2
unc_iio_data_req_of_cpu.mem_write.part0ÂÂÂÂÂÂÂ uncore_iio_0
unc_iio_data_req_of_cpu.mem_write.part0ÂÂÂÂÂÂÂ uncore_iio_5
unc_iio_data_req_of_cpu.mem_write.part0ÂÂÂÂÂÂÂ uncore_iio_3
unc_iio_data_req_of_cpu.mem_write.part0ÂÂÂÂÂÂÂ uncore_iio_1
unc_iio_data_req_of_cpu.mem_write.part1ÂÂÂÂÂÂÂ 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 <yao.jin@xxxxxxxxxxxxxxx>
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 <jolsa@xxxxxxxxxx>
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/1587120084-18990-2-git-send-email-john.garry@xxxxxxxxxx/
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?
I just thought that it fixes d4953f7ef1a2, as I found that the pointer equality
fails from that commit. I assume the parse-events code was sound before then (in
that regard). That's all I know :)
Thanks!
For 3cdc5c2cb924a, I just think it should use strcmp for pmu_name comparison
rather than using pointer. But I'm OK to add d4953f7ef1a2 in fixes clauses. :)
Thanks
Jin Yao
thanks,
jirka
cheers
---
ÂÂ tools/perf/util/parse-events.c | 5 ++---
ÂÂ 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,
ÂÂÂÂÂÂÂÂÂÂÂ * event. That can be used to distinguish the leader from
ÂÂÂÂÂÂÂÂÂÂÂ * other members, even they have the same event name.
ÂÂÂÂÂÂÂÂÂÂÂ */
-ÂÂÂÂÂÂÂ if ((leader != evsel) && (leader->pmu_name == evsel->pmu_name)) {
+ÂÂÂÂÂÂÂ if ((leader != evsel) &&
+ÂÂÂÂÂÂÂÂÂÂÂ !strcmp(leader->pmu_name, evsel->pmu_name)) {
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ is_leader = false;
ÂÂÂÂÂÂÂÂÂÂÂÂÂÂ continue;
ÂÂÂÂÂÂÂÂÂÂ }
-ÂÂÂÂÂÂÂ /* The name is always alias name */
-ÂÂÂÂÂÂÂ WARN_ON(strcmp(leader->name, evsel->name));
ÂÂÂÂÂÂÂÂÂÂ /* Store the leader event for each PMU */
ÂÂÂÂÂÂÂÂÂÂ leaders[nr_pmu++] = (uintptr_t) evsel;
--
2.17.1
.
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