perf_counter: Provide a way to enable counters on exec

This provides a way to mark a counter to be enabled on the next
exec. This is useful for measuring the total activity of a
program without including overhead from the process that
launches it.

This also changes the perf stat command to use this new
facility.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <19017.43927.838745.689203@cargo.ozlabs.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 3 insertions, 3 deletions

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 201ef2367dcb..2e03524a1de0 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -116,8 +116,9 @@ static void create_perf_stat_counter(int counter, int pid)
                                         fd[cpu][counter], strerror(errno));
                 }
         } else {
-                attr->inherit   = inherit;
-                attr->disabled  = 1;
+                attr->inherit        = inherit;
+                attr->disabled       = 1;
+                attr->enable_on_exec = 1;
 
                 fd[0][counter] = sys_perf_counter_open(attr, pid, -1, -1, 0);
                 if (fd[0][counter] < 0 && verbose)
@@ -262,7 +263,6 @@ static int run_perf_stat(int argc, const char **argv)
          * Enable counters and exec the command:
          */
         t0 = rdclock();
-        prctl(PR_TASK_PERF_COUNTERS_ENABLE);
 
         close(go_pipe[1]);
         wait(&status);