perf counters: implement PERF_COUNT_TASK_CLOCK

Impact: add new perf-counter type

The 'task clock' counter counts the amount of time a task is executing,
in nanoseconds. It stops ticking when a task is scheduled out either due
to it blocking, sleeping or it being preempted.

This counter type is a Linux kernel based abstraction, it is available
even if the hardware does not support native hardware performance counters.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 2 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 68f6e3ad531f..30c0ec8c1ee3 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -50,8 +50,11 @@ enum hw_event_types {
          */
         PERF_COUNT_CPU_CLOCK            = -1,
         PERF_COUNT_TASK_CLOCK           = -2,
-        PERF_COUNT_PAGE_FAULTS          = -3,
-        PERF_COUNT_CONTEXT_SWITCHES     = -4,
+        /*
+         * Future software events:
+         */
+        /* PERF_COUNT_PAGE_FAULTS       = -3,
+           PERF_COUNT_CONTEXT_SWITCHES  = -4, */
 };
 
 /*