Track how many pages trigger fallback strategies in GC

src/heap/mark-compact.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/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 2014 matching lines @@
   }
 }
 
 
 // Sweep the heap for overflowed objects, clear their overflow bits, and
 // push them on the marking stack.  Stop early if the marking stack fills
 // before sweeping completes.  If sweeping completes, there are no remaining
 // overflowed objects in the heap so the overflow flag on the markings stack
 // is cleared.
 void MarkCompactCollector::RefillMarkingDeque() {
+  isolate()->CountUsage(v8::Isolate::UseCounterFeature::kMarkDequeOverflow);
   DCHECK(marking_deque_.overflowed());
 
   DiscoverGreyObjectsInNewSpace(heap(), &marking_deque_);
   if (marking_deque_.IsFull()) return;
 
   DiscoverGreyObjectsInSpace(heap(), &marking_deque_,
                              heap()->old_pointer_space());
   if (marking_deque_.IsFull()) return;
 
   DiscoverGreyObjectsInSpace(heap(), &marking_deque_, heap()->old_data_space());
@@ skipping 2456 matching lines @@
           &slots_buffer_allocator_, target_page->slots_buffer_address(),
           SlotTypeForRMode(rmode), rinfo->pc(), SlotsBuffer::FAIL_ON_OVERFLOW);
     }
     if (!success) {
       EvictEvacuationCandidate(target_page);
     }
   }
 }
 
 
+void MarkCompactCollector::EvictEvacuationCandidate(Page* page) {
+  if (FLAG_trace_fragmentation) {
+    PrintF("Page %p is too popular. Disabling evacuation.\n",
+           reinterpret_cast<void*>(page));
+  }
+
+  isolate()->CountUsage(v8::Isolate::UseCounterFeature::kSlotsBufferOverflow);
+
+  // TODO(gc) If all evacuation candidates are too popular we
+  // should stop slots recording entirely.
+  page->ClearEvacuationCandidate();
+
+  // We were not collecting slots on this page that point
+  // to other evacuation candidates thus we have to
+  // rescan the page after evacuation to discover and update all
+  // pointers to evacuated objects.
+  if (page->owner()->identity() == OLD_DATA_SPACE) {
+    evacuation_candidates_.RemoveElement(page);
+  } else {
+    page->SetFlag(Page::RESCAN_ON_EVACUATION);
+  }
+}
+
+
 void MarkCompactCollector::RecordCodeEntrySlot(Address slot, Code* target) {
   Page* target_page = Page::FromAddress(reinterpret_cast<Address>(target));
   if (target_page->IsEvacuationCandidate() &&
       !ShouldSkipEvacuationSlotRecording(reinterpret_cast<Object**>(slot))) {
     if (!SlotsBuffer::AddTo(&slots_buffer_allocator_,
                             target_page->slots_buffer_address(),
                             SlotsBuffer::CODE_ENTRY_SLOT, slot,
                             SlotsBuffer::FAIL_ON_OVERFLOW)) {
       EvictEvacuationCandidate(target_page);
     }
@@ skipping 75 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }
 }  // namespace v8::internal