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author | Jin Yao <yao.jin@linux.intel.com> | 2018-01-16 23:43:08 +0800 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-02-27 11:29:21 -0300 |
commit | ab6c79b819f5a50cf41a11ebec17bef63b530333 (patch) | |
tree | 9124764bf20e56d0267d4453777f2d924a2a5dc8 /tools/perf/util/evsel.c | |
parent | 853745f5e6d95faaae6381c9a01dbd43de992fb3 (diff) | |
download | linux-ab6c79b819f5a50cf41a11ebec17bef63b530333.tar.bz2 |
perf stat: Ignore error thread when enabling system-wide --per-thread
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
Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1516117388-10120-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
-rw-r--r-- | tools/perf/util/evsel.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index ef351688b797..b56e1c2ddaee 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1915,6 +1915,9 @@ try_fallback: goto fallback_missing_features; } out_close: + if (err) + threads->err_thread = thread; + do { while (--thread >= 0) { close(FD(evsel, cpu, thread)); |