Add API to get total stopped-world marking time

New public function is GC_get_stopped_mark_total_time().

* alloc.c [!NO_CLOCK] (stopped_mark_total_time,
stopped_mark_total_ns_frac): New static variable.
* alloc.c [!NO_CLOCK] (GC_get_stopped_mark_total_time): New API
function definition.
* alloc.c [!NO_CLOCK] (GC_stopped_mark): Define start_time_valid,
ns_frac_diff local variables; call GET_TIME() also if
measure_performance; add TODO item (about code duplication); update
stopped_mark_total_time and stopped_mark_total_ns_frac values.
* alloc.c (GC_stopped_mark): Move logging of "Marking for collection"
upper to be before GET_TIME(start_time).
* include/gc/gc.h (GC_get_full_gc_total_time): Refine documentation.
* include/gc/gc.h (GC_get_stopped_mark_total_time): New API prototype.
* tests/gctest.c [!NO_CLOCK] (check_heap_stats): Call
GC_get_stopped_mark_total_time() to report total stopped-world marking
time.

1 files changed, 8 insertions, 2 deletions

diff --git a/include/gc/gc.h b/include/gc/gc.h
index 06048c6e..c72a3532 100644
--- a/include/gc/gc.h
+++ b/include/gc/gc.h
@@ -479,12 +479,18 @@ GC_API GC_word GC_CALL GC_get_allocd_bytes_per_finalizer(void);
 GC_API void GC_CALL GC_start_performance_measurement(void);
 
 /* Get the total time of all full collections since the start of the    */
-/* performance measurements.  The measurement unit is one millisecond.  */
-/* Note that the returned value wraps around on overflow.               */
+/* performance measurements.  Includes time spent in the supplementary  */
+/* actions like blacklists promotion, marks clearing, free lists        */
+/* reconstruction and objects finalization.  The measurement unit is a  */
+/* millisecond.  Note that the returned value wraps around on overflow. */
 /* The function does not use any synchronization.  Defined only if the  */
 /* library has been compiled without NO_CLOCK.                          */
 GC_API unsigned long GC_CALL GC_get_full_gc_total_time(void);
 
+/* Same as GC_get_full_gc_total_time but takes into account all mark    */
+/* phases with the world stopped and nothing else.                      */
+GC_API unsigned long GC_CALL GC_get_stopped_mark_total_time(void);
+
 /* Set whether the GC will allocate executable memory pages or not.     */
 /* A non-zero argument instructs the collector to allocate memory with  */
 /* the executable flag on.  Must be called before the collector is      */