Commit-ID: e965bea1ad1a8062b306f7fcc5c3e05dc5213b7c
Gitweb: http://git.kernel.org/tip/e965bea1ad1a8062b306f7fcc5c3e05dc5213b7c
Author: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Fri, 12 Dec 2014 16:25:33 -0300
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 16 Dec 2014 13:38:26 -0300
perf evlist: Improve the strerror_mmap method
Considering the per user locked pages limit, improve the message when a
user uses multiple simultaneous perf mmap calls:
When the request is more than the current maximum:
[acme@ssdandy linux]$ trace -m 128 usleep 1
Error: Operation not permitted.
Hint: Check /proc/sys/kernel/perf_event_mlock_kb (516 kB) setting.
Hint: Tried using 516 kB.
Hint: Try 'sudo sh -c "echo 1032 > /proc/sys/kernel/perf_event_mlock_kb"', or
Hint: Try using a smaller -m/--mmap-pages value.
[acme@ssdandy linux]$
And when the limit is less than that:
[acme@ssdandy linux]$ trace -m 512 usleep 1
Error: Operation not permitted.
Hint: Check /proc/sys/kernel/perf_event_mlock_kb (2056 kB) setting.
Hint: Tried using 2052 kB.
Hint: Try using a smaller -m/--mmap-pages value.
[acme@ssdandy linux]$
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Don Zickus <dzickus@xxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-yqdie3c8qvdgenwleri267d4@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/evlist.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index d661f25..7847f38 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1487,16 +1487,25 @@ int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused,
int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, size_t size)
{
char sbuf[STRERR_BUFSIZE], *emsg = strerror_r(err, sbuf, sizeof(sbuf));
- int pages_attempted = evlist->mmap_len / 1024, pages_max_per_user;
+ int pages_attempted = evlist->mmap_len / 1024, pages_max_per_user, printed = 0;
switch (err) {
case EPERM:
sysctl__read_int("kernel/perf_event_mlock_kb", &pages_max_per_user);
- scnprintf(buf, size, "Error:\t%s.\n"
+ printed += scnprintf(buf + printed, size - printed,
+ "Error:\t%s.\n"
"Hint:\tCheck /proc/sys/kernel/perf_event_mlock_kb (%d kB) setting.\n"
- "Hint:\tTried using %zd kB.\n"
- "Hint:\tTry using a smaller -m/--mmap-pages value.",
+ "Hint:\tTried using %zd kB.\n",
emsg, pages_max_per_user, pages_attempted);
+
+ if (pages_attempted >= pages_max_per_user) {
+ printed += scnprintf(buf + printed, size - printed,
+ "Hint:\tTry 'sudo sh -c \"echo %d > /proc/sys/kernel/perf_event_mlock_kb\"', or\n",
+ pages_max_per_user + pages_attempted);
+ }
+
+ printed += scnprintf(buf + printed, size - printed,
+ "Hint:\tTry using a smaller -m/--mmap-pages value.");
break;
default:
scnprintf(buf, size, "%s", emsg);
--
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