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@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-yqdie3c8qvdgenwleri267d4@git.kernel.orgSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent e5d4a290
...@@ -1487,16 +1487,25 @@ int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused, ...@@ -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) 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)); 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) { switch (err) {
case EPERM: case EPERM:
sysctl__read_int("kernel/perf_event_mlock_kb", &pages_max_per_user); 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:\tCheck /proc/sys/kernel/perf_event_mlock_kb (%d kB) setting.\n"
"Hint:\tTried using %zd kB.\n" "Hint:\tTried using %zd kB.\n",
"Hint:\tTry using a smaller -m/--mmap-pages value.",
emsg, pages_max_per_user, pages_attempted); 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; break;
default: default:
scnprintf(buf, size, "%s", emsg); scnprintf(buf, size, "%s", emsg);
......
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