Just tested. But looks it's not OK for '--per-thread' case.
jinyao@skl:~/$ ./perf stat --per-thread
WARNING: Ignored open failure for pid 1
WARNING: Ignored open failure for pid 2
WARNING: Ignored open failure for pid 4
WARNING: Ignored open failure for pid 6
WARNING: Ignored open failure for pid 7
WARNING: Ignored open failure for pid 8
WARNING: Ignored open failure for pid 9
WARNING: Ignored open failure for pid 10
......
WARNING: Ignored open failure for pid 11783
WARNING: Ignored open failure for pid 12275
WARNING: Ignored open failure for pid 31733
WARNING: Ignored open failure for pid 31737
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
Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
>= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
Disallow raw tracepoint access by users without CAP_SYS_ADMIN
>= 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
Thanks
Jin Yao
On 1/16/2018 8:51 PM, Jiri Olsa wrote:
On Tue, Jan 16, 2018 at 11:43:08PM +0800, Jin Yao wrote:
If we execute 'perf stat --per-thread' with non-root account
(even set kernel.perf_event_paranoid = -1 yet), it reports the error:
jinyao@skl:~$ perf stat --per-thread
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
Ignore mlock limit after perf_event_mlock_kb without CAP_IPC_LOCK
= 0: Disallow ftrace function tracepoint by users without CAP_SYS_ADMIN
Disallow raw tracepoint access by users without CAP_SYS_ADMIN
= 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
Perhaps the ptrace rule doesn't allow to trace some processes. But anyway
the global --per-thread mode had better ignore such errors and continue
working on other threads.
This patch will record the index of error thread in perf_evsel__open()
and remove this thread before retrying.
For example (run with non-root, kernel.perf_event_paranoid isn't set):
jinyao@skl:~$ perf stat --per-thread
^C
Performance counter stats for 'system wide':
vmstat-3458 6.171984 cpu-clock:u (msec) #
0.000 CPUs utilized
perf-3670 0.515599 cpu-clock:u (msec) #
0.000 CPUs utilized
vmstat-3458 1,163,643 cycles:u #
0.189 GHz
perf-3670 40,881 cycles:u #
0.079 GHz
vmstat-3458 1,410,238 instructions:u #
1.21 insn per cycle
perf-3670 3,536 instructions:u #
0.09 insn per cycle
vmstat-3458 288,937 branches:u #
46.814 M/sec
perf-3670 936 branches:u #
1.815 M/sec
vmstat-3458 15,195 branch-misses:u #
5.26% of all branches
perf-3670 76 branch-misses:u #
8.12% of all branches
12.651675247 seconds time elapsed
could we use the existing code like in attached patch?
we might also swap following warning for some generic one:
WARNING: Ignored open failure for pid 28392
jirka
---
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 98bf9d32f222..f9d4d3ad6fc5 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -276,6 +276,9 @@ static int create_perf_stat_counter(struct perf_evsel
*evsel)
attr->enable_on_exec = 1;
}
+ if (stat_config.aggr_mode == AGGR_THREAD)
+ evsel->ignore_missing_thread = true;
+
if (target__has_cpu(&target) && !target__has_per_thread(&target))
return perf_evsel__open_per_cpu(evsel, perf_evsel__cpus(evsel));
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 8f971a2301d1..509ee175bc97 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1656,7 +1656,7 @@ static bool ignore_missing_thread(struct perf_evsel
*evsel,
return false;
/* The -ESRCH is perf event syscall errno for pid's not found. */
- if (err != -ESRCH)
+ if (err != -ESRCH && err != -EACCES)
return false;
/* If there's only one thread, let it fail. */
