perf record: Mention paranoid sysctl when failing to create counter

[acme@mica linux-2.6-tip]$ perf record -a -f
   Fatal: Permission error - are you root?
 	 Consider tweaking /proc/sys/kernel/perf_event_paranoid.

 [acme@mica linux-2.6-tip]$

Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1268333592-30872-2-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 771533ced6a803d23886214d5551df1f0db440b1..6e4a39328b3363367ca930d123804599172409ef 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -280,7 +280,8 @@ try_again:
                int err = errno;
 
                if (err == EPERM || err == EACCES)
-                       die("Permission error - are you root?\n");
+                       die("Permission error - are you root?\n"
+                           "\t Consider tweaking /proc/sys/kernel/perf_event_paranoid.\n");
                else if (err ==  ENODEV && profile_cpu != -1)
                        die("No such device - did you specify an out-of-range profile CPU?\n");