src/hotspot/share/gc/epsilon/epsilonArguments.cpp

rev 52363 : 8232051: Epsilon should warn about Xms/Xmx/AlwaysPreTouch configuration
Reviewed-by: zgu

@@ -44,17 +44,29 @@
   // Forcefully exit when OOME is detected. Nothing we can do at that point.
   if (FLAG_IS_DEFAULT(ExitOnOutOfMemoryError)) {
     FLAG_SET_DEFAULT(ExitOnOutOfMemoryError, true);
   }
 
+  // Warn users that non-resizable heap might be better for some configurations.
+  // We are not adjusting the heap size by ourselves, because it affects startup time.
+  if (InitialHeapSize != MaxHeapSize) {
+    log_warning(gc)("Consider setting -Xms equal to -Xmx to avoid resizing hiccups");
+  }
+
+  // Warn users that AlwaysPreTouch might be better for some configurations.
+  // We are not turning this on by ourselves, because it affects startup time.
+  if (FLAG_IS_DEFAULT(AlwaysPreTouch) && !AlwaysPreTouch) {
+    log_warning(gc)("Consider enabling -XX:+AlwaysPreTouch to avoid memory commit hiccups");
+  }
+
   if (EpsilonMaxTLABSize < MinTLABSize) {
-    warning("EpsilonMaxTLABSize < MinTLABSize, adjusting it to " SIZE_FORMAT, MinTLABSize);
+    log_warning(gc)("EpsilonMaxTLABSize < MinTLABSize, adjusting it to " SIZE_FORMAT, MinTLABSize);
     EpsilonMaxTLABSize = MinTLABSize;
   }
 
   if (!EpsilonElasticTLAB && EpsilonElasticTLABDecay) {
-    warning("Disabling EpsilonElasticTLABDecay because EpsilonElasticTLAB is disabled");
+    log_warning(gc)("Disabling EpsilonElasticTLABDecay because EpsilonElasticTLAB is disabled");
     FLAG_SET_DEFAULT(EpsilonElasticTLABDecay, false);
   }
 
 #ifdef COMPILER2
   // Enable loop strip mining: there are still non-GC safepoints, no need to make it worse