perf_hooks: fix miscounted gc performance entry starttime (#43066)

PR-URL: #43066
Fixes: #43062
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: meixg

src/node_perf.cc

@@ -159,8 +159,10 @@ void MarkGarbageCollectionEnd(
   if (LIKELY(!state->observers[NODE_PERFORMANCE_ENTRY_TYPE_GC]))
     return;
 
-  double start_time = state->performance_last_gc_start_mark / 1e6;
-  double duration = (PERFORMANCE_NOW() / 1e6) - start_time;
+  double start_time =
+      (state->performance_last_gc_start_mark - timeOrigin) / 1e6;
+  double duration =
+      (PERFORMANCE_NOW() / 1e6) - (state->performance_last_gc_start_mark / 1e6);
 
   std::unique_ptr<GCPerformanceEntry> entry =
       std::make_unique<GCPerformanceEntry>(

test/parallel/test-performance-gc.js

@@ -35,6 +35,7 @@ const kinds = [
     assert.strictEqual(entry.flags, NODE_PERFORMANCE_GC_FLAGS_FORCED);
     assert.strictEqual(entry.detail.flags, NODE_PERFORMANCE_GC_FLAGS_FORCED);
     assert.strictEqual(typeof entry.startTime, 'number');
+    assert(entry.startTime < 1e4, 'startTime should be relative to performance.timeOrigin.');
     assert.strictEqual(typeof entry.duration, 'number');
     obs.disconnect();
   }));