[tip:perf/core] perf stat: Fall weak group back even for EBADF

From: tip-bot for Andi Kleen
Date: Fri Sep 22 2017 - 12:38:23 EST


Commit-ID: 35c1980eb3d1acb3cac11c38252339399dca77e3
Gitweb: http://git.kernel.org/tip/35c1980eb3d1acb3cac11c38252339399dca77e3
Author: Andi Kleen <ak@xxxxxxxxxxxxxxx>
AuthorDate: Tue, 5 Sep 2017 14:13:24 -0700
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 13 Sep 2017 09:49:16 -0300

perf stat: Fall weak group back even for EBADF

It's not possible to run a package event and a per cpu event in the same
group. This is used by some of the power metrics. They work correctly
when not using a group.

Normally weak groups should handle that, but in this case EBADF is
returned instead of the normal EINVAL.

$ strace -e perf_event_open ./perf stat -v -e '{cstate_pkg/c2-residency/,msr/tsc/}:W' -a sleep 1
Using CPUID GenuineIntel-6-3E
perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, PERF_FLAG_FD_CLOEXEC) = -1 EINVAL (Invalid argument)
perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = -1 EINVAL (Invalid argument)
perf_event_open({type=0x17 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, -1, 0) = 3
perf_event_open({type=0x7 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 0, 3, 0) = 4
perf_event_open({type=0x7 /* PERF_TYPE_??? */, size=PERF_ATTR_SIZE_VER5, config=0, ...}, -1, 1, 0, 0) = -1 EBADF (Bad file descriptor)

and perf errors out.

Make weak groups trigger a fall back for EBADF too. Then this case works correctly:

$ perf stat -v -e '{cstate_pkg/c2-residency/,msr/tsc/}:W' -a sleep 1
Using CPUID GenuineIntel-6-3E
Weak group for cstate_pkg/c2-residency//2 failed
cstate_pkg/c2-residency/: 476709882 1000598460 1000598460
msr/tsc/: 39625837911 12007369110 12007369110

Performance counter stats for 'system wide':

476,709,882 cstate_pkg/c2-residency/
39,625,837,911 msr/tsc/

1.000697588 seconds time elapsed

This fixes perf stat -M Power ...

$ perf stat -M Power --metric-only -a sleep 1

Performance counter stats for 'system wide':

Turbo_Utilization C3_Core_Residency C6_Core_Residency C7_Core_Residency C2_Pkg_Residency C3_Pkg_Residency C6_Pkg_Residency C7_Pkg_Residency
1.0 0.7 30.0 0.0 0.9 0.1 0.4 0.0

1.001240740 seconds time elapsed

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Link: http://lkml.kernel.org/r/20170905211324.32427-1-andi@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-stat.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 88f1d5f..dd52541 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -656,7 +656,7 @@ try_again:
if (create_perf_stat_counter(counter) < 0) {

/* Weak group failed. Reset the group. */
- if (errno == EINVAL &&
+ if ((errno == EINVAL || errno == EBADF) &&
counter->leader != counter &&
counter->weak_group) {
counter = perf_evsel__reset_weak_group(counter);