Commit de46d526 authored Apr 27, 2016 by Arnaldo Carvalho de Melo

perf evsel: Handle ENOMEM for perf_event_max_stack + PERF_SAMPLE_CALLCHAIN



When the kernel allows tweaking perf_event_max_stack and the event being
setup has PERF_SAMPLE_CALLCHAIN in its perf_event_attr.sample_type, tell
the user that tweaking /proc/sys/kernel/perf_event_max_stack may solve
the problem.

Before:

  # echo 32000 > /proc/sys/kernel/perf_event_max_stack
  # perf record -g usleep 1
  Error:
  The sys_perf_event_open() syscall returned with 12 (Cannot allocate memory) for event (cycles:ppp).
  /bin/dmesg may provide additional information.
  No CONFIG_PERF_EVENTS=y kernel support configured?

  #

After:

  # echo 64000 > /proc/sys/kernel/perf_event_max_stack
  # perf record -g usleep 1
  Error:
  Not enough memory to setup event with callchain.
  Hint: Try tweaking /proc/sys/kernel/perf_event_max_stack
  Hint: Current value: 64000
  #

Suggested-by: David Ahern <dsahern@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/n/tip-ebv0orelj1s1ye857vhb82ov@git.kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent 1a71476e

tools/perf/util/evsel.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -2325,6 +2325,14 @@ int perf_evsel__open_strerror(struct perf_evsel evsel, struct target target,
		"Probably the maximum number of open file descriptors has been reached.\n"
		"Hint: Try again after reducing the number of events.\n"
		"Hint: Try increasing the limit with 'ulimit -n <limit>'");
		case ENOMEM:
		if ((evsel->attr.sample_type & PERF_SAMPLE_CALLCHAIN) != 0 &&
		access("/proc/sys/kernel/perf_event_max_stack", F_OK) == 0)
		return scnprintf(msg, size,
		"Not enough memory to setup event with callchain.\n"
		"Hint: Try tweaking /proc/sys/kernel/perf_event_max_stack\n"
		"Hint: Current value: %d", sysctl_perf_event_max_stack);
		break;
		case ENODEV:
		if (target->cpu_list)
		return scnprintf(msg, size, "%s",

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