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>
1 file changed