[PATCH] perf stat: Skip duration_time in setup_system_wide

Jin Yao
2020-09-22T01:50:30Z

Some metrics (such as DRAM_BW_Use) consists of uncore events and
duration_time. For uncore events, counter->core.system_wide is
true. But for duration_time, counter->core.system_wide is false
so target.system_wide is set to false.

Then 'enable_on_exec' is set in perf_event_attr of uncore event.
Kernel will return error when trying to open the uncore event.

This patch skips the duration_time in setup_system_wide then
target.system_wide will be set to true for the evlist of uncore
events + duration_time.

Before (tested on skylake desktop):

# perf stat -M DRAM_BW_Use -- sleep 1
Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (arb/event=0x84,umask=0x1/).
/bin/dmesg | grep -i perf may provide additional information.

After:

# perf stat -M DRAM_BW_Use -- sleep 1

Performance counter stats for 'system wide':

169 arb/event=0x84,umask=0x1/ # 0.00 DRAM_BW_Use
40,427 arb/event=0x81,umask=0x1/
1,000,902,197 ns duration_time

1.000902197 seconds time elapsed

Fixes: 648b5af3f3ae ("libperf: Move 'system_wide' from 'struct evsel' to 'struct perf_evsel'")
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
---
tools/perf/builtin-stat.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 7f8d756d9408..9bcc93bc0973 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -2047,8 +2047,10 @@ static void setup_system_wide(int forks)
struct evsel *counter;

evlist__for_each_entry(evsel_list, counter) {
- if (!counter->core.system_wide)
+ if (!counter->core.system_wide &&
+ strcmp(counter->name, "duration_time")) {
return;
+ }
}

if (evsel_list->core.nr_entries)
--
2.17.1