Commit 18e60939 authored Dec 19, 2011 by Nelson Elhage Committed by Arnaldo Carvalho de Melo Dec 23, 2011

perf: builtin-record: Provide advice if mmap'ing fails with EPERM.

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.

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/1324301972-22740-3-git-send-email-nelhage@nelhage.com

Signed-off-by: Nelson Elhage <nelhage@nelhage.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

parent f41612f4

tools/perf/builtin-record.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -272,8 +272,15 @@ static void perf_record__open(struct perf_record *rec)
		exit(-1);
		}

		if (perf_evlist__mmap(evlist, opts->mmap_pages, false) < 0)
		if (perf_evlist__mmap(evlist, opts->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", opts->mmap_pages);
		die("failed to mmap with %d (%s)\n", errno, strerror(errno));
		}

		if (rec->file_new)
		session->evlist = evlist;