8301641: NativeMemoryUsageTotal event uses reserved value for committed field

Reviewed-by: eosterlund, stefank

Author: kstefanj

src/hotspot/share/services/nmtUsage.cpp

@@ -115,7 +115,7 @@ size_t NMTUsage::total_reserved() const {
 }
 
 size_t NMTUsage::total_committed() const {
-  return _malloc_total + _vm_total.reserved;
+  return _malloc_total + _vm_total.committed;
 }
 
 size_t NMTUsage::reserved(MEMFLAGS flag) const {

test/jdk/jdk/jfr/event/runtime/TestNativeMemoryUsageEvents.java

@@ -147,6 +147,17 @@ private static void verifyHeapGrowth(List<RecordedEvent> events) throws Exceptio
         assertGreaterThan(lastSample, firstSample, "heap should have grown and NMT should show that");
     }
 
+    private static void verifyTotalDiffBetweenReservedAndCommitted(List<RecordedEvent> events) throws Exception {
+        RecordedEvent firstTotal = events.stream()
+                .filter(e -> e.getEventType().getName().equals(UsageTotalEvent))
+                .findFirst().orElse(null);
+
+        // Verify that the first total event has more reserved than committed memory.
+        long firstReserved = firstTotal.getLong("reserved");
+        long firstCommitted = firstTotal.getLong("committed");
+        assertGreaterThan(firstReserved, firstCommitted, "initial reserved should be greater than initial committed");
+    }
+
     private static void verifyNoUsageEvents(List<RecordedEvent> events) throws Exception {
         Events.hasNotEvent(events, UsageEvent);
         Events.hasNotEvent(events, UsageTotalEvent);
@@ -167,6 +178,7 @@ public static void main(String[] args) throws Exception {
             if (nmtEnabled) {
                 verifyExpectedEventTypes(events);
                 verifyHeapGrowth(events);
+                verifyTotalDiffBetweenReservedAndCommitted(events);
             } else {
                 verifyNoUsageEvents(events);
             }