perf_counter: Full task tracing

In order to be able to distinguish between no samples due to
inactivity and no samples due to task ended, Arjan asked for
PERF_EVENT_EXIT events. This is useful to the boot delay
instrumentation (bootchart) app.

This patch changes the PERF_EVENT_FORK to be emitted on every
clone, and adds PERF_EVENT_EXIT to be emitted on task exit,
after the task's counters have been closed.

This task tracing is controlled through: attr.comm || attr.mmap
and through the new attr.task field.

Suggested-by: Arjan van de Ven <arjan@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Anton Blanchard <anton@samba.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
[ cleaned up perf_counter.h a bit ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 1 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index bd15d7a5f5ce..e604e6ef72dd 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -181,8 +181,9 @@ struct perf_counter_attr {
                                 freq           :  1, /* use freq, not period  */
                                 inherit_stat   :  1, /* per task counts       */
                                 enable_on_exec :  1, /* next exec enables     */
+                                task           :  1, /* trace fork/exit       */
 
-                                __reserved_1   : 51;
+                                __reserved_1   : 50;
 
         __u32                   wakeup_events;  /* wakeup every n events */
         __u32                   __reserved_2;
@@ -311,6 +312,15 @@ enum perf_event_type {
         /*
          * struct {
          *      struct perf_event_header        header;
+         *      u32                             pid, ppid;
+         *      u32                             tid, ptid;
+         * };
+         */
+        PERF_EVENT_EXIT                 = 4,
+
+        /*
+         * struct {
+         *      struct perf_event_header        header;
          *      u64                             time;
          *      u64                             id;
          *      u64                             stream_id;
@@ -323,6 +333,7 @@ enum perf_event_type {
          * struct {
          *      struct perf_event_header        header;
          *      u32                             pid, ppid;
+         *      u32                             tid, ptid;
          * };
          */
         PERF_EVENT_FORK                 = 7,