diff options
| author | Arnaldo Carvalho de Melo <acme@redhat.com> | 2014-12-12 16:07:47 -0300 |
|---|---|---|
| committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2014-12-16 13:38:26 -0300 |
| commit | 0a2138b28fd56eeb3852133691c881409885ee3f (patch) | |
| tree | b383a9e64ad31f0a801ec0275ccd0fbd705cc51f /tools | |
| parent | 41e950c033b7df997d4b38653efe6554be9b96a7 (diff) | |
| download | lwn-0a2138b28fd56eeb3852133691c881409885ee3f.tar.gz lwn-0a2138b28fd56eeb3852133691c881409885ee3f.zip | |
perf evlist: Fixup brown paper bag on "hint" for --mmap-pages cmdline arg
When failing due to asking for a number of mmap pages that is more than
the max, it was suggesting that an even bigger number of mmap pages
should be specified, doh, au contraire!
Before:
[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 using a bigger -m/--mmap-pages value.
[acme@ssdandy linux]$
After:
[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 using a smaller -m/--mmap-pages value.
[acme@ssdandy linux]$
And to (really) clarify what happens above, when what the user requests
is <= max and even then it fails, a changeset is being made to tell that
this is a per user limit, not per process (in the above example there
was another 'perf trace' running for this user, which was using all the
pages it could use).
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-8qope8lxb898narnq5kmu2gf@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/perf/util/evlist.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index bb5dfc5d1e75..de7515dd683a 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -1495,7 +1495,7 @@ int perf_evlist__strerror_mmap(struct perf_evlist *evlist, int err, char *buf, s scnprintf(buf, size, "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 bigger -m/--mmap-pages value.", + "Hint:\tTry using a smaller -m/--mmap-pages value.", emsg, value, evlist->mmap_len / 1024); break; default: |