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From: Nelson Elhage <nelhage@nelhage.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>, Ingo Molnar <mingo@elte.hu>,
	Arnaldo Carvalho de Melo <acme@ghostprotocols.net>,
	linux-kernel@vger.kernel.org, Nelson Elhage <nelhage@nelhage.com>
Subject: [PATCH 2/3] perf: builtin-record: Provide advice if mmap'ing fails with EPERM.
Date: Mon, 19 Dec 2011 08:39:31 -0500	[thread overview]
Message-ID: <1324301972-22740-3-git-send-email-nelhage@nelhage.com> (raw)
In-Reply-To: <1324301972-22740-1-git-send-email-nelhage@nelhage.com>

This failure is most likely due to running up against the
kernel.perf_event_mlock_kb sysctl, so we can tell the user what to do
to fix the issue.

Signed-off-by: Nelson Elhage <nelhage@nelhage.com>
---
 tools/perf/builtin-record.c |    9 ++++++++-
 1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 6ab58cc..45b23c1 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -358,8 +358,15 @@ try_again:
 		exit(-1);
 	}
 
-	if (perf_evlist__mmap(evlist, mmap_pages, false) < 0)
+	if (perf_evlist__mmap(evlist, mmap_pages, false) < 0) {
+		if (errno == EPERM)
+			die("Permission error mapping pages.\n"
+			    "Consider increasing "
+			    "/proc/sys/kernel/perf_event_mlock_kb,\n"
+			    "or try again with a smaller value of -m/--mmap_pages.\n"
+			    "(current value: %d)\n", mmap_pages);
 		die("failed to mmap with %d (%s)\n", errno, strerror(errno));
+	}
 
 	if (file_new)
 		session->evlist = evlist;
-- 
1.7.4.41.g50b8f


  parent reply	other threads:[~2011-12-19 13:40 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-12-19 13:39 [PATCH 0/3] perf: builtin-record: Be more helpful when running up against mlock limits Nelson Elhage
2011-12-19 13:39 ` [PATCH 1/3] perf: __perf_evlist__mmap: Fix errno value on failed map Nelson Elhage
2011-12-19 15:33   ` Namhyung Kim
2011-12-19 16:29     ` Arnaldo Carvalho de Melo
2011-12-20 17:55     ` Arnaldo Carvalho de Melo
2011-12-21  8:43   ` [tip:perf/core] perf evlist: Fix errno value reporting on failed mmap tip-bot for Nelson Elhage
2011-12-19 13:39 ` Nelson Elhage [this message]
2011-12-29 20:50   ` [tip:perf/core] perf: builtin-record: Provide advice if mmap' ing fails with EPERM tip-bot for Nelson Elhage
2011-12-19 13:39 ` [PATCH 3/3] perf: builtin-record: Document and check that mmap_pages must be a power of two Nelson Elhage
2011-12-29 20:50   ` [tip:perf/core] " tip-bot for Nelson Elhage

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