perf,tools: error out unsupported group leader immediately for perf stat

PATCH In review [email protected] 3 participants 5 messages Jun 11, 2015 – Jun 12, 2015 perf events

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[email protected]

author

2015-06-11 13:46 UTC #0 lore raw

PATCH 1/1 perf,tools: error out unsupported group leader immediately for perf stat

From: Kan Liang <[email protected]>

perf stat ignores the unsupported event and continue to count supported event. But if the unsupported event is group leader, perf tool will crash. After applying this patch, the unsupported group leader will error out immediately.

Without this patch:

$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
perf: util/evsel.c:1009: get_group_fd: Assertion `!(fd == -1)' failed.
Aborted (core dumped)

With this patch:

$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
Error:
The node-prefetch-refs event is not supported.

Signed-off-by Kan Liang <[email protected]>

---
 tools/perf/builtin-stat.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

tools/perf/builtin-stat.c +4 -1

index ff3d258..b24ecee 100644
@@ -549,7 +549,10 @@ static int __run_perf_stat(int argc, const char **argv)
 					ui__warning("%s event is not supported by the kernel.\n",
 						    perf_evsel__name(counter));
 				counter->supported = false;
-				continue;
+
+				if ((counter->leader != counter) ||
+				    !(counter->leader->nr_members > 1))
+					continue;
 			}
 
 			perf_evsel__open_strerror(counter, &target,

Signature · 1 line

1.8.3.1

Arnaldo Carvalho de Melo

maintainer

2015-06-11 14:03 UTC #1 lore raw

Em Thu, Jun 11, 2015 at 02:32:40AM -0400, [email protected] escreveu:

Quoted 6 lines

perf stat ignores the unsupported event and continue to count supported event. But if the unsupported event is group leader, perf tool will crash. After applying this patch, the unsupported group leader will error out immediately.
Without this patch:

Quoted 8 lines

$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
perf: util/evsel.c:1009: get_group_fd: Assertion `!(fd == -1)' failed.
Aborted (core dumped)

With this patch:

$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
Error:
The node-prefetch-refs event is not supported.

I get something different, maybe I am missing a patch?

With this patch:

[acme@zoo linux]$ perf stat -x, -e '{node-prefetch-refs,cycles}' -- sleep 1 Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (node-prefetch-refs).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?
[acme@zoo linux]$

Applying it anyway, as it avoids a core dump and the message, albeit not optimal, points to a problem with that event.

Have you tried this with other tools, like perf record?

- Arnaldo

Liang, Kan

author

2015-06-11 14:26 UTC #2 lore raw

Quoted 22 lines

Em Thu, Jun 11, 2015 at 02:32:40AM -0400, [email protected] escreveu:
Quoted 6 lines
perf stat ignores the unsupported event and continue to count supported event. But if the unsupported event is group leader, perf tool will crash. After applying this patch, the unsupported group leader will error out immediately.
Without this patch:
Quoted 8 lines
$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
perf: util/evsel.c:1009: get_group_fd: Assertion `!(fd == -1)' failed.
Aborted (core dumped)
With this patch:
$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
Error:
The node-prefetch-refs event is not supported.
I get something different, maybe I am missing a patch?
With this patch:

Quoted 8 lines

[acme@zoo linux]$ perf stat -x, -e '{node-prefetch-refs,cycles}' -- sleep 1 Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (node-prefetch-refs).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?
[acme@zoo linux]$

I don't have other patches for this issue.
It looks they have different error code, ENOENT VS. EINVAL. I have no idea why.

Quoted 4 lines

Applying it anyway, as it avoids a core dump and the message, albeit not optimal, points to a problem with that event.
Have you tried this with other tools, like perf record?

Yes. Perf record and perf top will error out immediately if any unsupported event found. So they don't have such issue.

Thanks,
Kan

Quoted 2 lines

- Arnaldo

Arnaldo Carvalho de Melo

maintainer

2015-06-11 14:30 UTC #3 lore raw

Em Thu, Jun 11, 2015 at 02:26:47PM +0000, Liang, Kan escreveu:

Quoted 17 lines

Quoted 8 lines
Em Thu, Jun 11, 2015 at 02:32:40AM -0400, [email protected] escreveu:
Quoted 4 lines
With this patch:
$ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
Error:
The node-prefetch-refs event is not supported.
I get something different, maybe I am missing a patch?
Quoted 8 lines
With this patch:
[acme@zoo linux]$ perf stat -x, -e '{node-prefetch-refs,cycles}' -- sleep 1 Error:
The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (node-prefetch-refs).
/bin/dmesg may provide additional information.
No CONFIG_PERF_EVENTS=y kernel support configured?

Quoted 3 lines

I don't have other patches for this issue.
It looks they have different error code, ENOENT VS. EINVAL. I have no idea why.

Well, here I have:

[acme@zoo ~]$ uname -a
Linux zoo.ghostprotocols.net 3.19.7-200.fc21.x86_64 #1 SMP Thu May 7 22:00:21 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

I am rebooting now, due to an unrelated reason, to 4.1.0-rc5+, lets see if this explains this discrepancy...

Quoted 7 lines

Quoted 4 lines
Applying it anyway, as it avoids a core dump and the message, albeit not optimal, points to a problem with that event.
Have you tried this with other tools, like perf record?
Yes. Perf record and perf top will error out immediately if any unsupported event found. So they don't have such issue.

Ok, need to revisit the event setup code again and remove the code duplication once and for all :-\

- Arnaldo

tip-bot for Kan Liang

merge bot

2015-06-12 08:52 UTC #4 lore raw

[tip:perf/core] perf stat: Error out unsupported group leader immediately

In reply to [email protected]

perf stat: Error out unsupported group leader immediately

Commit-ID:  cb5ef60067c11cc8887122f6f168c21941c5d624
Gitweb:     http://git.kernel.org/tip/cb5ef60067c11cc8887122f6f168c21941c5d624
Author:     Kan Liang <[email protected]>
AuthorDate: Thu, 11 Jun 2015 02:32:40 -0400
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Thu, 11 Jun 2015 11:07:40 -0300

perf stat: Error out unsupported group leader immediately

Without this patch:

  $ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
  perf: util/evsel.c:1009: get_group_fd: Assertion `!(fd == -1)' failed.
  Aborted (core dumped)

With this patch:

  $ perf stat -x, -e '{node-prefetch-refs,cycles}' --  sleep 1
  Error:
  The node-prefetch-refs event is not supported.

Commiter note: Here I got a different output, but no core dump:

Signed-off-by Kan Liang <[email protected]>

Tested-by Arnaldo Carvalho de Melo <[email protected]>

Cc Andi Kleen <[email protected]>

Link http://lkml.kernel.org/r/[email protected] open here

Signed-off-by Arnaldo Carvalho de Melo <[email protected]>

---
 tools/perf/builtin-stat.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

tools/perf/builtin-stat.c +4 -1

index ff3d258..b24ecee 100644
@@ -549,7 +549,10 @@ static int __run_perf_stat(int argc, const char **argv)
 					ui__warning("%s event is not supported by the kernel.\n",
 						    perf_evsel__name(counter));
 				counter->supported = false;
-				continue;
+
+				if ((counter->leader != counter) ||
+				    !(counter->leader->nr_members > 1))
+					continue;
 			}
 
 			perf_evsel__open_strerror(counter, &target,