Added histogram to track distribution of requested idle notifications.

src/heap.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/accessors.h"
 #include "src/api.h"
 #include "src/base/once.h"
 #include "src/base/utils/random-number-generator.h"
@@ skipping 35 matching lines @@
 
 namespace v8 {
 namespace internal {
 
 
 Heap::Heap()
     : amount_of_external_allocated_memory_(0),
       amount_of_external_allocated_memory_at_last_global_gc_(0),
       isolate_(NULL),
       code_range_size_(0),
-// semispace_size_ should be a power of 2 and old_generation_size_ should be
-// a multiple of Page::kPageSize.
+      // semispace_size_ should be a power of 2 and old_generation_size_ should
+      // be
+      // a multiple of Page::kPageSize.

[rmcilroy, 2014/07/25 09:38:29]

move up to line above

       reserved_semispace_size_(8 * (kPointerSize / 4) * MB),
-      max_semi_space_size_(8 * (kPointerSize / 4)  * MB),
+      max_semi_space_size_(8 * (kPointerSize / 4) * MB),
       initial_semispace_size_(Page::kPageSize),
       max_old_generation_size_(700ul * (kPointerSize / 4) * MB),
       max_executable_size_(256ul * (kPointerSize / 4) * MB),
-// Variables set based on semispace_size_ and old_generation_size_ in
-// ConfigureHeap.
-// Will be 4 * reserved_semispace_size_ to ensure that young
-// generation can be aligned to its size.
+      // Variables set based on semispace_size_ and old_generation_size_ in
+      // ConfigureHeap.
+      // Will be 4 * reserved_semispace_size_ to ensure that young
+      // generation can be aligned to its size.
       maximum_committed_(0),
       survived_since_last_expansion_(0),
       sweep_generation_(0),
       always_allocate_scope_depth_(0),
       contexts_disposed_(0),
       global_ic_age_(0),
       flush_monomorphic_ics_(false),
       scan_on_scavenge_pages_(0),
       new_space_(this),
       old_pointer_space_(NULL),
@@ skipping 46 matching lines @@
       incremental_marking_(this),
       number_idle_notifications_(0),
       last_idle_notification_gc_count_(0),
       last_idle_notification_gc_count_init_(false),
       mark_sweeps_since_idle_round_started_(0),
       gc_count_at_last_idle_gc_(0),
       scavenges_since_last_idle_round_(kIdleScavengeThreshold),
       full_codegen_bytes_generated_(0),
       crankshaft_codegen_bytes_generated_(0),
       gcs_since_last_deopt_(0),
+      idle_notification_histogram_(NULL),
 #ifdef VERIFY_HEAP
       no_weak_object_verification_scope_depth_(0),
 #endif
       allocation_sites_scratchpad_length_(0),
       promotion_queue_(this),
       configured_(false),
       external_string_table_(this),
       chunks_queued_for_free_(NULL),
       gc_callbacks_depth_(0) {
   // Allow build-time customization of the max semispace size. Building
@@ skipping 4118 matching lines @@
   const int kMinHintForIncrementalMarking = 10;
   // Minimal hint that allows to do full GC.
   const int kMinHintForFullGC = 100;
   intptr_t size_factor = Min(Max(hint, 20), kMaxHint) / 4;
   // The size factor is in range [5..250]. The numbers here are chosen from
   // experiments. If you changes them, make sure to test with
   // chrome/performance_ui_tests --gtest_filter="GeneralMixMemoryTest.*
   intptr_t step_size =
       size_factor * IncrementalMarking::kAllocatedThreshold;
 
+  isolate()->stats_table()->AddHistogramSample(idle_notification_histogram_,
+                                               hint);
   HistogramTimerScope idle_notification_scope(
       isolate_->counters()->gc_idle_notification());
 
   if (contexts_disposed_ > 0) {
     contexts_disposed_ = 0;
     int mark_sweep_time = Min(TimeMarkSweepWouldTakeInMs(), 1000);
     if (hint >= mark_sweep_time && !FLAG_expose_gc &&
         incremental_marking()->IsStopped()) {
       HistogramTimerScope scope(isolate_->counters()->gc_context());
       CollectAllGarbage(kReduceMemoryFootprintMask,
@@ skipping 844 matching lines @@
   // call Heap::TearDown() to release allocated memory.
   //
   // If the heap is not yet configured (e.g. through the API), configure it.
   // Configuration is based on the flags new-space-size (really the semispace
   // size) and old-space-size if set or the initial values of semispace_size_
   // and old_generation_size_ otherwise.
   if (!configured_) {
     if (!ConfigureHeapDefault()) return false;
   }
 
+  idle_notification_histogram_ = isolate()->stats_table()->CreateHistogram(
+      "V8.IdleNotification", 0, kMaxIdleNotificationHistogramSample,

[rmcilroy, 2014/07/25 09:38:29]

ditto (V8.IdleNotificationHint or V8.IdleGCAllottedTime).

+      kMaxIdleNotificationHistogramSample + 1);
+
   base::CallOnce(&initialize_gc_once, &InitializeGCOnce);
 
   MarkMapPointersAsEncoded(false);
 
   // Set up memory allocator.
   if (!isolate_->memory_allocator()->SetUp(MaxReserved(), MaxExecutableSize()))
       return false;
 
   // Set up new space.
   if (!new_space_.SetUp(reserved_semispace_size_, max_semi_space_size_)) {
@@ skipping 1305 matching lines @@
       static_cast<int>(object_sizes_last_time_[index]));
   CODE_AGE_LIST_COMPLETE(ADJUST_LAST_TIME_OBJECT_COUNT)
 #undef ADJUST_LAST_TIME_OBJECT_COUNT
 
   MemCopy(object_counts_last_time_, object_counts_, sizeof(object_counts_));
   MemCopy(object_sizes_last_time_, object_sizes_, sizeof(object_sizes_));
   ClearObjectStats();
 }
 
 } }  // namespace v8::internal