diff --git a/src/heap/gc-tracer.h b/src/heap/gc-tracer.h
new file mode 100644
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+++ b/src/heap/gc-tracer.h
@@ -0,0 +1,401 @@
+// 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.
+
+#ifndef V8_HEAP_GC_TRACER_H_
+#define V8_HEAP_GC_TRACER_H_
+
+#include "src/base/platform/platform.h"
+
+namespace v8 {
+namespace internal {
+
+// A simple ring buffer class with maximum size known at compile time.
+// The class only implements the functionality required in GCTracer.
+template <typename T, size_t MAX_SIZE>
+class RingBuffer {
+ public:
+  class const_iterator {
+   public:
+    const_iterator() : index_(0), elements_(NULL) {}
+
+    const_iterator(size_t index, const T* elements)
+        : index_(index), elements_(elements) {}
+
+    bool operator==(const const_iterator& rhs) const {
+      return elements_ == rhs.elements_ && index_ == rhs.index_;
+    }
+
+    bool operator!=(const const_iterator& rhs) const {
+      return elements_ != rhs.elements_ || index_ != rhs.index_;
+    }
+
+    operator const T*() const { return elements_ + index_; }
+
+    const T* operator->() const { return elements_ + index_; }
+
+    const T& operator*() const { return elements_[index_]; }
+
+    const_iterator& operator++() {
+      index_ = (index_ + 1) % (MAX_SIZE + 1);
+      return *this;
+    }
+
+    const_iterator& operator--() {
+      index_ = (index_ + MAX_SIZE) % (MAX_SIZE + 1);
+      return *this;
+    }
+
+   private:
+    size_t index_;
+    const T* elements_;
+  };
+
+  RingBuffer() : begin_(0), end_(0) {}
+
+  bool empty() const { return begin_ == end_; }
+  size_t size() const {
+    return (end_ - begin_ + MAX_SIZE + 1) % (MAX_SIZE + 1);
+  }
+  const_iterator begin() const { return const_iterator(begin_, elements_); }
+  const_iterator end() const { return const_iterator(end_, elements_); }
+  const_iterator back() const { return --end(); }
+  void push_back(const T& element) {
+    elements_[end_] = element;
+    end_ = (end_ + 1) % (MAX_SIZE + 1);
+    if (end_ == begin_) begin_ = (begin_ + 1) % (MAX_SIZE + 1);
+  }
+  void push_front(const T& element) {
+    begin_ = (begin_ + MAX_SIZE) % (MAX_SIZE + 1);
+    if (begin_ == end_) end_ = (end_ + MAX_SIZE) % (MAX_SIZE + 1);
+    elements_[begin_] = element;
+  }
+
+ private:
+  T elements_[MAX_SIZE + 1];
+  size_t begin_;
+  size_t end_;
+
+  DISALLOW_COPY_AND_ASSIGN(RingBuffer);
+};
+
+
+// GCTracer collects and prints ONE line after each garbage collector
+// invocation IFF --trace_gc is used.
+// TODO(ernstm): Unit tests.
+class GCTracer {
+ public:
+  class Scope {
+   public:
+    enum ScopeId {
+      EXTERNAL,
+      MC_MARK,
+      MC_SWEEP,
+      MC_SWEEP_NEWSPACE,
+      MC_SWEEP_OLDSPACE,
+      MC_SWEEP_CODE,
+      MC_SWEEP_CELL,
+      MC_SWEEP_MAP,
+      MC_EVACUATE_PAGES,
+      MC_UPDATE_NEW_TO_NEW_POINTERS,
+      MC_UPDATE_ROOT_TO_NEW_POINTERS,
+      MC_UPDATE_OLD_TO_NEW_POINTERS,
+      MC_UPDATE_POINTERS_TO_EVACUATED,
+      MC_UPDATE_POINTERS_BETWEEN_EVACUATED,
+      MC_UPDATE_MISC_POINTERS,
+      MC_WEAKCOLLECTION_PROCESS,
+      MC_WEAKCOLLECTION_CLEAR,
+      MC_WEAKCOLLECTION_ABORT,
+      MC_FLUSH_CODE,
+      NUMBER_OF_SCOPES
+    };
+
+    Scope(GCTracer* tracer, ScopeId scope) : tracer_(tracer), scope_(scope) {
+      start_time_ = base::OS::TimeCurrentMillis();
+    }
+
+    ~Scope() {
+      DCHECK(scope_ < NUMBER_OF_SCOPES);  // scope_ is unsigned.
+      tracer_->current_.scopes[scope_] +=
+          base::OS::TimeCurrentMillis() - start_time_;
+    }
+
+   private:
+    GCTracer* tracer_;
+    ScopeId scope_;
+    double start_time_;
+
+    DISALLOW_COPY_AND_ASSIGN(Scope);
+  };
+
+
+  class AllocationEvent {
+   public:
+    // Default constructor leaves the event uninitialized.
+    AllocationEvent() {}
+
+    AllocationEvent(double duration, intptr_t allocation_in_bytes);
+
+    // Time spent in the mutator during the end of the last garbage collection
+    // to the beginning of the next garbage collection.
+    double duration_;
+
+    // Memory allocated in the new space during the end of the last garbage
+    // collection to the beginning of the next garbage collection.
+    intptr_t allocation_in_bytes_;
+  };
+
+  class Event {
+   public:
+    enum Type { SCAVENGER = 0, MARK_COMPACTOR = 1, START = 2 };
+
+    // Default constructor leaves the event uninitialized.
+    Event() {}
+
+    Event(Type type, const char* gc_reason, const char* collector_reason);
+
+    // Returns a string describing the event type.
+    const char* TypeName(bool short_name) const;
+
+    // Type of event
+    Type type;
+
+    const char* gc_reason;
+    const char* collector_reason;
+
+    // Timestamp set in the constructor.
+    double start_time;
+
+    // Timestamp set in the destructor.
+    double end_time;
+
+    // Size of objects in heap set in constructor.
+    intptr_t start_object_size;
+
+    // Size of objects in heap set in destructor.
+    intptr_t end_object_size;
+
+    // Size of memory allocated from OS set in constructor.
+    intptr_t start_memory_size;
+
+    // Size of memory allocated from OS set in destructor.
+    intptr_t end_memory_size;
+
+    // Total amount of space either wasted or contained in one of free lists
+    // before the current GC.
+    intptr_t start_holes_size;
+
+    // Total amount of space either wasted or contained in one of free lists
+    // after the current GC.
+    intptr_t end_holes_size;
+
+    // Size of new space objects in constructor.
+    intptr_t new_space_object_size;
+
+    // Number of incremental marking steps since creation of tracer.
+    // (value at start of event)
+    int cumulative_incremental_marking_steps;
+
+    // Incremental marking steps since
+    // - last event for SCAVENGER events
+    // - last MARK_COMPACTOR event for MARK_COMPACTOR events
+    int incremental_marking_steps;
+
+    // Bytes marked since creation of tracer (value at start of event).
+    intptr_t cumulative_incremental_marking_bytes;
+
+    // Bytes marked since
+    // - last event for SCAVENGER events
+    // - last MARK_COMPACTOR event for MARK_COMPACTOR events
+    intptr_t incremental_marking_bytes;
+
+    // Cumulative duration of incremental marking steps since creation of
+    // tracer. (value at start of event)
+    double cumulative_incremental_marking_duration;
+
+    // Duration of incremental marking steps since
+    // - last event for SCAVENGER events
+    // - last MARK_COMPACTOR event for MARK_COMPACTOR events
+    double incremental_marking_duration;
+
+    // Cumulative pure duration of incremental marking steps since creation of
+    // tracer. (value at start of event)
+    double cumulative_pure_incremental_marking_duration;
+
+    // Duration of pure incremental marking steps since
+    // - last event for SCAVENGER events
+    // - last MARK_COMPACTOR event for MARK_COMPACTOR events
+    double pure_incremental_marking_duration;
+
+    // Longest incremental marking step since start of marking.
+    // (value at start of event)
+    double longest_incremental_marking_step;
+
+    // Amounts of time spent in different scopes during GC.
+    double scopes[Scope::NUMBER_OF_SCOPES];
+  };
+
+  static const int kRingBufferMaxSize = 10;
+
+  typedef RingBuffer<Event, kRingBufferMaxSize> EventBuffer;
+
+  typedef RingBuffer<AllocationEvent, kRingBufferMaxSize> AllocationEventBuffer;
+
+  explicit GCTracer(Heap* heap);
+
+  // Start collecting data.
+  void Start(GarbageCollector collector, const char* gc_reason,
+             const char* collector_reason);
+
+  // Stop collecting data and print results.
+  void Stop();
+
+  // Log an allocation throughput event.
+  void AddNewSpaceAllocationTime(double duration, intptr_t allocation_in_bytes);
+
+  // Log an incremental marking step.
+  void AddIncrementalMarkingStep(double duration, intptr_t bytes);
+
+  // Log time spent in marking.
+  void AddMarkingTime(double duration) {
+    cumulative_marking_duration_ += duration;
+  }
+
+  // Time spent in marking.
+  double cumulative_marking_duration() const {
+    return cumulative_marking_duration_;
+  }
+
+  // Log time spent in sweeping on main thread.
+  void AddSweepingTime(double duration) {
+    cumulative_sweeping_duration_ += duration;
+  }
+
+  // Time spent in sweeping on main thread.
+  double cumulative_sweeping_duration() const {
+    return cumulative_sweeping_duration_;
+  }
+
+  // Compute the mean duration of the last scavenger events. Returns 0 if no
+  // events have been recorded.
+  double MeanScavengerDuration() const {
+    return MeanDuration(scavenger_events_);
+  }
+
+  // Compute the max duration of the last scavenger events. Returns 0 if no
+  // events have been recorded.
+  double MaxScavengerDuration() const { return MaxDuration(scavenger_events_); }
+
+  // Compute the mean duration of the last mark compactor events. Returns 0 if
+  // no events have been recorded.
+  double MeanMarkCompactorDuration() const {
+    return MeanDuration(mark_compactor_events_);
+  }
+
+  // Compute the max duration of the last mark compactor events. Return 0 if no
+  // events have been recorded.
+  double MaxMarkCompactorDuration() const {
+    return MaxDuration(mark_compactor_events_);
+  }
+
+  // Compute the mean step duration of the last incremental marking round.
+  // Returns 0 if no incremental marking round has been completed.
+  double MeanIncrementalMarkingDuration() const;
+
+  // Compute the max step duration of the last incremental marking round.
+  // Returns 0 if no incremental marking round has been completed.
+  double MaxIncrementalMarkingDuration() const;
+
+  // Compute the average incremental marking speed in bytes/millisecond.
+  // Returns 0 if no events have been recorded.
+  intptr_t IncrementalMarkingSpeedInBytesPerMillisecond() const;
+
+  // Compute the average scavenge speed in bytes/millisecond.
+  // Returns 0 if no events have been recorded.
+  intptr_t ScavengeSpeedInBytesPerMillisecond() const;
+
+  // Compute the max mark-sweep speed in bytes/millisecond.
+  // Returns 0 if no events have been recorded.
+  intptr_t MarkCompactSpeedInBytesPerMillisecond() const;
+
+  // Allocation throughput in the new space in bytes/millisecond.
+  // Returns 0 if no events have been recorded.
+  intptr_t NewSpaceAllocationThroughputInBytesPerMillisecond() const;
+
+ private:
+  // Print one detailed trace line in name=value format.
+  // TODO(ernstm): Move to Heap.
+  void PrintNVP() const;
+
+  // Print one trace line.
+  // TODO(ernstm): Move to Heap.
+  void Print() const;
+
+  // Compute the mean duration of the events in the given ring buffer.
+  double MeanDuration(const EventBuffer& events) const;
+
+  // Compute the max duration of the events in the given ring buffer.
+  double MaxDuration(const EventBuffer& events) const;
+
+  // Pointer to the heap that owns this tracer.
+  Heap* heap_;
+
+  // Current tracer event. Populated during Start/Stop cycle. Valid after Stop()
+  // has returned.
+  Event current_;
+
+  // Previous tracer event.
+  Event previous_;
+
+  // Previous MARK_COMPACTOR event.
+  Event previous_mark_compactor_event_;
+
+  // RingBuffers for SCAVENGER events.
+  EventBuffer scavenger_events_;
+
+  // RingBuffers for MARK_COMPACTOR events.
+  EventBuffer mark_compactor_events_;
+
+  // RingBuffer for allocation events.
+  AllocationEventBuffer allocation_events_;
+
+  // Cumulative number of incremental marking steps since creation of tracer.
+  int cumulative_incremental_marking_steps_;
+
+  // Cumulative size of incremental marking steps (in bytes) since creation of
+  // tracer.
+  intptr_t cumulative_incremental_marking_bytes_;
+
+  // Cumulative duration of incremental marking steps since creation of tracer.
+  double cumulative_incremental_marking_duration_;
+
+  // Cumulative duration of pure incremental marking steps since creation of
+  // tracer.
+  double cumulative_pure_incremental_marking_duration_;
+
+  // Longest incremental marking step since start of marking.
+  double longest_incremental_marking_step_;
+
+  // Total marking time.
+  // This timer is precise when run with --print-cumulative-gc-stat
+  double cumulative_marking_duration_;
+
+  // Total sweeping time on the main thread.
+  // This timer is precise when run with --print-cumulative-gc-stat
+  // TODO(hpayer): Account for sweeping time on sweeper threads. Add a
+  // different field for that.
+  // TODO(hpayer): This timer right now just holds the sweeping time
+  // of the initial atomic sweeping pause. Make sure that it accumulates
+  // all sweeping operations performed on the main thread.
+  double cumulative_sweeping_duration_;
+
+  // Holds the new space top pointer recorded at the end of the last garbage
+  // collection.
+  intptr_t new_space_top_after_gc_;
+
+  DISALLOW_COPY_AND_ASSIGN(GCTracer);
+};
+}
+}  // namespace v8::internal
+
+#endif  // V8_HEAP_GC_TRACER_H_