From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Thu, 11 Dec 2014 21:04:10 +0000 (-0300)
Subject: perf trace: Provide a better explanation when mmap fails
X-Git-Tag: omap-for-v3.20/drop-legacy-3517~25^2~2^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e09b18d4907992d3d615b215c1abf585721b2810;p=pandora-kernel.git

perf trace: Provide a better explanation when mmap fails

If we ask for a mmap lenght than the max configured via the relevant
sysctl, provide a better warning, instead of just expanding the EPERM
returned:

[acme@ssdandy ~]$ trace -m 256 -e nanosleep sleep 2
Error:	Operation not permitted.
Hint:	Check /proc/sys/kernel/perf_event_mlock_kb (516 kB) setting.
Hint:	Tried using 1028 kB.
Hint:	Try using a bigger -m/--mmap-pages value.

[acme@ssdandy ~]$ trace -m 128 -e nanosleep sleep 2
  2001.280 (2000.403 ms): nanosleep(rqtp: 0x7fff89a8a7f0) = 0
[acme@ssdandy ~]$

An upcoming patch will autotune the request for non-root users when -m
is not used.

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-cdvxfz2gycetbkopm9sna1qp@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

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