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Groups > linux.kernel > #1621718
| From | Arnaldo Carvalho de Melo <acme@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 03/18] perf evsel: Return exact sub event which failed with EPERM for wildcards |
| Date | 2017-04-12 03:00 +0200 |
| Message-ID | <tveNA-5Wv-19@gated-at.bofh.it> (permalink) |
| References | <tveNA-5Wv-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Jin Yao <yao.jin@linux.intel.com>
The kernel has a special check for a specific irq_vectors trace event.
TRACE_EVENT_PERF_PERM(irq_work_exit,
is_sampling_event(p_event) ? -EPERM : 0);
The perf-record fails for this irq_vectors event when it is present,
like when 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 in understanding what went wrong when this event is
present:
After the patch:
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.
......
Committer notes:
So we have a lot of irq_vectors events:
[root@jouet ~]# perf list irq_vectors:*
List of pre-defined events (to be used in -e):
irq_vectors:call_function_entry [Tracepoint event]
irq_vectors:call_function_exit [Tracepoint event]
irq_vectors:call_function_single_entry [Tracepoint event]
irq_vectors:call_function_single_exit [Tracepoint event]
irq_vectors:deferred_error_apic_entry [Tracepoint event]
irq_vectors:deferred_error_apic_exit [Tracepoint event]
irq_vectors:error_apic_entry [Tracepoint event]
irq_vectors:error_apic_exit [Tracepoint event]
irq_vectors:irq_work_entry [Tracepoint event]
irq_vectors:irq_work_exit [Tracepoint event]
irq_vectors:local_timer_entry [Tracepoint event]
irq_vectors:local_timer_exit [Tracepoint event]
irq_vectors:reschedule_entry [Tracepoint event]
irq_vectors:reschedule_exit [Tracepoint event]
irq_vectors:spurious_apic_entry [Tracepoint event]
irq_vectors:spurious_apic_exit [Tracepoint event]
irq_vectors:thermal_apic_entry [Tracepoint event]
irq_vectors:thermal_apic_exit [Tracepoint event]
irq_vectors:threshold_apic_entry [Tracepoint event]
irq_vectors:threshold_apic_exit [Tracepoint event]
irq_vectors:x86_platform_ipi_entry [Tracepoint event]
irq_vectors:x86_platform_ipi_exit [Tracepoint event]
#
And some may be sampled:
[root@jouet ~]# perf record -e irq_vectors:local* sleep 20s
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.020 MB perf.data (2 samples) ]
[root@jouet ~]# perf report -D | egrep 'stats:|events:'
Aggregated stats:
TOTAL events: 155
MMAP events: 144
COMM events: 2
EXIT events: 1
SAMPLE events: 2
MMAP2 events: 4
FINISHED_ROUND events: 1
TIME_CONV events: 1
irq_vectors:local_timer_entry stats:
TOTAL events: 1
SAMPLE events: 1
irq_vectors:local_timer_exit stats:
TOTAL events: 1
SAMPLE events: 1
[root@jouet ~]#
But, as shown in the tracepoint definition at the start of this message,
some, like "irq_vectors:irq_work_exit", may not be sampled, just counted,
i.e. if we try to sample, as when using 'perf record', we get an error:
[root@jouet ~]# perf record -e irq_vectors:irq_work_exit
Error:
You may not have permission to collect system-wide stats.
Consider tweaking /proc/sys/kernel/perf_event_paranoid,
<SNIP>
The error message is misleading, this patch will help in pointing out
what is the event causing such an error, but the error message needs
improvement, i.e. we need to figure out a way to check if a tracepoint
is counting only, like this one, when all we can do is to count it with
'perf stat', at most printing the delta using interval printing, as in:
[root@jouet ~]# perf stat -I 5000 -e irq_vectors:irq_work_*
# time counts unit events
5.000168871 0 irq_vectors:irq_work_entry
5.000168871 0 irq_vectors:irq_work_exit
10.000676730 0 irq_vectors:irq_work_entry
10.000676730 0 irq_vectors:irq_work_exit
15.001122415 0 irq_vectors:irq_work_entry
15.001122415 0 irq_vectors:irq_work_exit
20.001298051 0 irq_vectors:irq_work_entry
20.001298051 0 irq_vectors:irq_work_exit
25.001485020 1 irq_vectors:irq_work_entry
25.001485020 1 irq_vectors:irq_work_exit
30.001658706 0 irq_vectors:irq_work_entry
30.001658706 0 irq_vectors:irq_work_exit
^C 32.045711878 0 irq_vectors:irq_work_entry
32.045711878 0 irq_vectors:irq_work_exit
[root@jouet ~]#
But at least, when we use a wildcard, this patch helps a bit.
Signed-off-by: Yao Jin <yao.jin@linux.intel.com>
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: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1491566932-503-1-git-send-email-yao.jin@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.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 9dc7e2d6e48a..8f5d86bd3501 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"
--
2.9.3
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[GIT PULL 00/18] perf/core improvements and fixes Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 09/18] perf annotate s390: Fix perf annotate error -95 (4.10 regression) Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 03/18] perf evsel: Return exact sub event which failed with EPERM for wildcards Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 14/18] perf annotate: Process attr and build_id records Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 16/18] perf tools: Do not print missing features in pipe-mode Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 07/18] perf tools: Refactor the code to strip command name with {l,r}trim() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 12/18] perf inject: Copy events when reordering events in pipe mode Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 08/18] perf string: Simplify ltrim() implementation Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 01/18] perf callchains: Switch from strtok() to strtok_r() when parsing options Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 17/18] perf annotate: Refactor the code to parse disassemble lines with {l,r}trim() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 10/18] perf annotate s390: Implement jump types for perf annotate Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 06/18] perf pmu: Refactor wordwrap() with ltrim() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 13/18] perf tools: Describe pipe mode in perf.data-file-fomat.txt Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 15/18] perf session: Don't rely on evlist in pipe mode Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 18/18] perf annotate: Use stripped line instead of raw disassemble line Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 05/18] perf ui browser: Refactor the code to parse color configs with ltrim() Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
[PATCH 02/18] perf script: Use strtok_r() when parsing output field list Arnaldo Carvalho de Melo <acme@kernel.org> - 2017-04-12 03:00 +0200
Re: [GIT PULL 00/18] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2017-04-12 07:40 +0200
Re: [GIT PULL 00/18] perf/core improvements and fixes Christian Borntraeger <borntraeger@de.ibm.com> - 2017-04-12 09:20 +0200
Re: [GIT PULL 00/18] perf/core improvements and fixes Ingo Molnar <mingo@kernel.org> - 2017-04-12 09:30 +0200
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