From: Arnaldo Carvalho de Melo <a...@redhat.com>
[ Upstream commit 97365e81366f5ca16a9ce66cff4dd4c5b0d9f4db ]
We should set attr.exclude_kernel when probing for attr.precise_ip
level, otherwise !CAP_SYS_ADMIN users will not default to skidless
samples in capable hardware.
The increase in the paranoid level in commit 0161028b7c8a ("perf/core:
Change the default paranoia level to 2") broke this, fix it by excluding
kernel samples when probing.
Before:
$ perf record usleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.018 MB perf.data (6 samples) ]
$ perf evlist -v
cycles:u: sample_freq: 4000, sample_type: IP|TID|TIME|PERIOD, exclude_kernel:
1
After:
$ perf record usleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.018 MB perf.data (8 samples) ]
$ perf evlist -v
cycles:ppp: sample_freq: 4000, sample_type: IP|TID|TIME|PERIOD,
exclude_kernel: 1, precise_ip: 3
^^^^^^^^^^^^^
^^^^^^^^^^^^^
^^^^^^^^^^^^^
$
To further clarify: we always set .exclude_kernel when non !CAP_SYS_ADMIN
users profile, its just on the attr.precise_ip probing that we weren't doing
so, fix it.
Cc: Adrian Hunter <adrian.hun...@intel.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: David Ahern <dsah...@gmail.com>
Cc: Jiri Olsa <jo...@kernel.org>
Cc: Namhyung Kim <namhy...@kernel.org>
Cc: Wang Nan <wangn...@huawei.com>
Fixes: 7f8d1ade1b19 ("perf tools: By default use the most precise "cycles" hw
counter available")
Link: http://lkml.kernel.org/n/tip-t2qttwhbnua62o5gt75cu...@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <a...@redhat.com>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
---
tools/perf/util/evsel.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 97fe0c80ff02..1c1291afd6a6 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -258,6 +258,7 @@ struct perf_evsel *perf_evsel__new_cycles(void)
struct perf_event_attr attr = {
.type = PERF_TYPE_HARDWARE,
.config = PERF_COUNT_HW_CPU_CYCLES,
+ .exclude_kernel = 1,
};
struct perf_evsel *evsel;
--
2.15.1
