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-rw-r--r--tools/perf/builtin-record.c9
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:
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;