path: root/tools
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authorNelson Elhage <nelhage@nelhage.com>2011-12-19 08:39:31 -0500
committerArnaldo Carvalho de Melo <acme@redhat.com>2011-12-23 16:44:34 -0200
commit18e6093904abfd51671ff5846c2fdaba9ebbf21b (patch)
tree5ff067b1fefef24fb8ba91496d7dcbf2a9f06f7d /tools
parentf41612f43be9575e1160460b08c3a760e6e27e1b (diff)
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>
Diffstat (limited to 'tools')
1 files changed, 8 insertions, 1 deletions
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f8fd14fb62ec..56bb4476e3ba 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -272,8 +272,15 @@ try_again:
- 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;