Messages in this thread Patch in this message | | | From | Nelson Elhage <> | Subject | [PATCH 2/3] perf: builtin-record: Provide advice if mmap'ing fails with EPERM. | Date | Mon, 19 Dec 2011 08:39:31 -0500 |
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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
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