[tip:perf/core] perf top: Add error message for EMFILE

[tip-bot for Namhyung Kim <namhyung@gmail.com>]

Commit-ID:  cdce445906852d90efdc773ca7ba460e6e41664d
Gitweb:     http://git.kernel.org/tip/cdce445906852d90efdc773ca7ba460e6e41664d
Author:     Namhyung Kim <namhyung@gmail.com>
AuthorDate: Sun, 8 Jan 2012 02:25:27 +0900
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Sun, 8 Jan 2012 13:26:11 -0200

perf top: Add error message for EMFILE

When a user tries to open so many events, perf_event_open syscall may
fail with EMFILE. Provide advise for that case.

Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1325957132-10600-3-git-send-email-namhyung@gmail.com
Signed-off-by: Namhyung Kim <namhyung@gmail.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-top.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index d89dec9..8f80df8 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -888,6 +888,10 @@ try_again:
 				ui__warning("The %s event is not supported.\n",
 					    event_name(counter));
 				goto out_err;
+			} else if (err == EMFILE) {
+				ui__warning("Too many events are opened.\n"
+					    "Try again after reducing the number of events\n");
+				goto out_err;
 			}
 
 			ui__warning("The sys_perf_event_open() syscall "