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Subject[PATCH v2 2/2] perf: Add error message for EMFILE
Date
When a user tries to open so many event on multiple tasks/cpus,
perf_event_open syscall may fail with EMFILE. Provide an advice
for that case.

Signed-off-by: Namhyung Kim <namhyung.kim@lge.com>
Cc: David Ahern <dsahern@gmail.com>
---
tools/perf/builtin-record.c | 5 +++++
tools/perf/builtin-stat.c | 4 ++++
tools/perf/builtin-top.c | 3 ++-
3 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 32870eef952f..a334008a1853 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -249,6 +249,11 @@ try_again:
ui__warning("The %s event is not supported.\n",
event_name(pos));
exit(EXIT_FAILURE);
+ } else if (err == EMFILE) {
+ ui__warning("Too many events are opened.\n"
+ "Try again after reducing the number of events,\n"
+ "tasks and/or cpus.\n");
+ exit(EXIT_FAILURE);
}

printf("\n");
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 459b8620a5d9..7c5421c7af06 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -477,6 +477,10 @@ static int run_perf_stat(int argc __used, const char **argv)
"\t Consider tweaking"
" /proc/sys/kernel/perf_event_paranoid or running as root.",
system_wide ? "system-wide " : "");
+ } else if (errno == EMFILE) {
+ error("Too many events are opened.\n"
+ "\t Try again after reducing the number of events,\n"
+ "\t tasks and/or cpus.");
} else {
error("open_counter returned with %d (%s). "
"/bin/dmesg may provide additional information.\n",
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index e8b033c074f9..987af3695218 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -899,7 +899,8 @@ try_again:
goto out_err;
} else if (err == EMFILE) {
ui__warning("Too many events are opened.\n"
- "Try again after reducing the number of events\n");
+ "Try again after reducing the number of events,\n"
+ "tasks and/or cpus.\n");
goto out_err;
}

--
1.7.9.rc1.dirty


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