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authorArnaldo Carvalho de Melo <acme@redhat.com>2014-12-12 22:07:47 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2014-12-16 19:38:26 +0300
commit0a2138b28fd56eeb3852133691c881409885ee3f (patch)
treeb383a9e64ad31f0a801ec0275ccd0fbd705cc51f /tools
parent41e950c033b7df997d4b38653efe6554be9b96a7 (diff)
downloadlinux-0a2138b28fd56eeb3852133691c881409885ee3f.tar.xz
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.c2
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: