Bug 1774651 - Add a MajorGC PerfStats metric r=smaug

Differential Revision: https://phabricator.services.mozilla.com/D149554

dom/base/CCGCScheduler.cpp

@@ -9,6 +9,7 @@
 #include "mozilla/CycleCollectedJSRuntime.h"
 #include "mozilla/ProfilerMarkers.h"
 #include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/PerfStats.h"
 #include "nsRefreshDriver.h"
 
 /*
@@ -232,6 +233,22 @@ void CCGCScheduler::NoteGCEnd() {
   }
 }
 
+void CCGCScheduler::NoteGCSliceEnd(TimeDuration aSliceDuration) {
+  if (mMajorGCReason == JS::GCReason::NO_REASON) {
+    // Internally-triggered GCs do not wait for the parent's permission to
+    // proceed. This flag won't be checked during an incremental GC anyway,
+    // but it better reflects reality.
+    mReadyForMajorGC = true;
+  }
+
+  // Subsequent slices should be INTER_SLICE_GC unless they are triggered by
+  // something else that provides its own reason.
+  mMajorGCReason = JS::GCReason::INTER_SLICE_GC;
+
+  mGCUnnotifiedTotalTime += aSliceDuration;
+  PerfStats::RecordMeasurement(PerfStats::Metric::MajorGC, aSliceDuration);
+}
+
 void CCGCScheduler::NoteCCBegin(CCReason aReason, TimeStamp aWhen,
                                 uint32_t aNumForgetSkippables,
                                 uint32_t aSuspected, uint32_t aRemovedPurples) {

dom/base/CCGCScheduler.h

@@ -288,20 +288,8 @@ class CCGCScheduler {
   void NoteCCEnd(const CycleCollectorResults& aResults, TimeStamp aWhen,
                  mozilla::TimeDuration aMaxSliceTime);
 
-  void NoteGCSliceEnd(TimeDuration aSliceDuration) {
-    if (mMajorGCReason == JS::GCReason::NO_REASON) {
-      // Internally-triggered GCs do not wait for the parent's permission to
-      // proceed. This flag won't be checked during an incremental GC anyway,
-      // but it better reflects reality.
-      mReadyForMajorGC = true;
-    }
-
-    // Subsequent slices should be INTER_SLICE_GC unless they are triggered by
-    // something else that provides its own reason.
-    mMajorGCReason = JS::GCReason::INTER_SLICE_GC;
-
-    mGCUnnotifiedTotalTime += aSliceDuration;
-  }
+  // A single slice has completed.
+  void NoteGCSliceEnd(TimeDuration aSliceDuration);
 
   bool GCRunnerFired(TimeStamp aDeadline);
   bool GCRunnerFiredDoGC(TimeStamp aDeadline, const GCRunnerStep& aStep);

tools/performance/PerfStats.h

@@ -47,7 +47,8 @@
   MACRO(JSBC_Compression)                \
   MACRO(JSBC_Decompression)              \
   MACRO(JSBC_IO_Read)                    \
-  MACRO(JSBC_IO_Write)
+  MACRO(JSBC_IO_Write)                   \
+  MACRO(MajorGC)
 
 namespace mozilla {