1 files changed, 16 insertions, 4 deletions

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 7847f3885081..ac808680e61c 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -893,10 +893,22 @@ out_unmap:
 
 static size_t perf_evlist__mmap_size(unsigned long pages)
 {
-        /* 512 kiB: default amount of unprivileged mlocked memory */
-        if (pages == UINT_MAX)
-                pages = (512 * 1024) / page_size;
-        else if (!is_power_of_2(pages))
+        if (pages == UINT_MAX) {
+                int max;
+
+                if (sysctl__read_int("kernel/perf_event_mlock_kb", &max) < 0) {
+                        /*
+                         * Pick a once upon a time good value, i.e. things look
+                         * strange since we can't read a sysctl value, but lets not
+                         * die yet...
+                         */
+                        max = 512;
+                } else {
+                        max -= (page_size / 1024);
+                }
+
+                pages = (max * 1024) / page_size;
+        } else if (!is_power_of_2(pages))
                 return 0;
 
         return (pages + 1) * page_size;