The kernel has a special check for irq_vectors trace event.
TRACE_EVENT_PERF_PERM(irq_work_exit,
is_sampling_event(p_event) ? -EPERM : 0);
The perf-record is failed for irq_vectors event if using a wildcard.
root@skl:/tmp# perf record -a -e irq_vectors:* sleep 2
Error:
You may not have permission to collect system-wide stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid,
which controls use of the performance events system by
unprivileged users (without CAP_SYS_ADMIN).
The current value is 2:
-1: Allow use of (almost) all events by all users
>= 0: Disallow raw tracepoint access by users without CAP_IOC_LOCK
>= 1: Disallow CPU event access by users without CAP_SYS_ADMIN
>= 2: Disallow kernel profiling by users without CAP_SYS_ADMIN
To make this setting permanent, edit /etc/sysctl.conf too, e.g.:
kernel.perf_event_paranoid = -1
This patch prints out the exact sub event that failed with EPERM
for wildcards to help user understanding easily.
For example,
root@skl:/tmp# perf record -a -e irq_vectors:* sleep 2
Error:
No permission to enable irq_vectors:irq_work_exit event.
You may not have permission to collect system-wide stats.
......
Signed-off-by: Jin Yao <yao....@linux.intel.com>
---
tools/perf/util/evsel.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 9dc7e2d..8f5d86b 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2457,11 +2457,17 @@ int perf_evsel__open_strerror(struct perf_evsel *evsel,
struct target *target,
int err, char *msg, size_t size)
{
char sbuf[STRERR_BUFSIZE];
+ int printed = 0;
switch (err) {
case EPERM:
case EACCES:
- return scnprintf(msg, size,
+ if (err == EPERM)
+ printed = scnprintf(msg, size,
+ "No permission to enable %s event.\n\n",
+ perf_evsel__name(evsel));
+
+ return scnprintf(msg + printed, size - printed,
"You may not have permission to collect %sstats.\n\n"
"Consider tweaking /proc/sys/kernel/perf_event_paranoid,\n"
"which controls use of the performance events system by\n"
--
2.7.4
