When allocation rate is low and we are close to the new space limit, we should perform a scavenge d…

src/heap/gc-idle-time-handler.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/flags.h"
 #include "src/heap/gc-idle-time-handler.h"
 #include "src/heap/gc-tracer.h"
 #include "src/utils.h"
 
 namespace v8 {
@@ skipping 111 matching lines @@
       kMaxScheduledIdleTime * scavenge_speed_in_bytes_per_ms;
 
   // If the limit is larger than the new space size, then scavenging used to be
   // really fast. We can take advantage of the whole new space.
   if (new_space_allocation_limit > new_space_size) {
     new_space_allocation_limit = new_space_size;
   }
 
   // We do not know the allocation throughput before the first scavenge.
   // TODO(hpayer): Estimate allocation throughput before the first scavenge.
-  if (new_space_allocation_throughput_in_bytes_per_ms == 0) {
-    new_space_allocation_limit =
-        static_cast<size_t>(new_space_size * kConservativeTimeRatio);
-  } else {
+  if (new_space_allocation_throughput_in_bytes_per_ms > 0) {
     // We have to trigger scavenge before we reach the end of new space.
     size_t adjust_limit = new_space_allocation_throughput_in_bytes_per_ms *
                           kTimeUntilNextIdleEvent;
     if (adjust_limit > new_space_allocation_limit) {
       new_space_allocation_limit = 0;
     } else {
       new_space_allocation_limit -= adjust_limit;
     }
   }
 
+  if (new_space_allocation_throughput_in_bytes_per_ms <
+      kLowAllocationThroughput) {
+    new_space_allocation_limit =
+        Min(new_space_allocation_limit,
+            static_cast<size_t>(new_space_size * kConservativeTimeRatio));
+  }
+
   // The allocated new space limit to trigger a scavange has to be at least
   // kMinimumNewSpaceSizeToPerformScavenge.
   if (new_space_allocation_limit < kMinimumNewSpaceSizeToPerformScavenge) {
     new_space_allocation_limit = kMinimumNewSpaceSizeToPerformScavenge;
   }
 
   if (scavenge_speed_in_bytes_per_ms == 0) {
     scavenge_speed_in_bytes_per_ms = kInitialConservativeScavengeSpeed;
   }
 
@@ skipping 108 matching lines @@
 
   size_t step_size = EstimateMarkingStepSize(
       static_cast<size_t>(kIncrementalMarkingStepTimeInMs),
       heap_state.incremental_marking_speed_in_bytes_per_ms);
   return GCIdleTimeAction::IncrementalMarking(step_size);
 }
 
 
 }
 }