diff --git a/runtime/gc/collector/mark_sweep.cc b/runtime/gc/collector/mark_sweep.cc
index 944ef8d..bb41b57 100644
--- a/runtime/gc/collector/mark_sweep.cc
+++ b/runtime/gc/collector/mark_sweep.cc
@@ -129,7 +129,10 @@
     ReaderMutexLock mu(Thread::Current(), *Locks::heap_bitmap_lock_);
     mark_bitmap_ = heap_->GetMarkBitmap();
   }
-
+  if (!clear_soft_references_) {
+    // Always clear soft references if a non-sticky collection.
+    clear_soft_references_ = GetGcType() != collector::kGcTypeSticky;
+  }
   // Do any pre GC verification.
   timings_.NewSplit("PreGcVerification");
   heap_->PreGcVerification(this);
diff --git a/runtime/gc/collector/semi_space.cc b/runtime/gc/collector/semi_space.cc
index 1366858..e82d533 100644
--- a/runtime/gc/collector/semi_space.cc
+++ b/runtime/gc/collector/semi_space.cc
@@ -65,6 +65,8 @@
 static constexpr bool kProtectFromSpace = true;
 static constexpr bool kClearFromSpace = true;
 static constexpr bool kStoreStackTraces = false;
+static constexpr bool kUseBytesPromoted = true;
+static constexpr size_t kBytesPromotedThreshold = 4 * MB;
 
 void SemiSpace::BindBitmaps() {
   timings_.StartSplit("BindBitmaps");
@@ -102,8 +104,10 @@
       generational_(generational),
       last_gc_to_space_end_(nullptr),
       bytes_promoted_(0),
+      bytes_promoted_since_last_whole_heap_collection_(0),
       whole_heap_collection_(true),
-      whole_heap_collection_interval_counter_(0) {
+      whole_heap_collection_interval_counter_(0),
+      collector_name_(name_) {
 }
 
 void SemiSpace::InitializePhase() {
@@ -150,14 +154,31 @@
       // collection, collect the whole heap (and reset the interval
       // counter to be consistent.)
       whole_heap_collection_ = true;
-      whole_heap_collection_interval_counter_ = 0;
+      if (!kUseBytesPromoted) {
+        whole_heap_collection_interval_counter_ = 0;
+      }
     }
     if (whole_heap_collection_) {
       VLOG(heap) << "Whole heap collection";
+      name_ = collector_name_ + " whole";
     } else {
       VLOG(heap) << "Bump pointer space only collection";
+      name_ = collector_name_ + " bps";
     }
   }
+
+  if (!clear_soft_references_) {
+    if (!generational_) {
+      // If non-generational, always clear soft references.
+      clear_soft_references_ = true;
+    } else {
+      // If generational, clear soft references if a whole heap collection.
+      if (whole_heap_collection_) {
+        clear_soft_references_ = true;
+      }
+    }
+  }
+
   Locks::mutator_lock_->AssertExclusiveHeld(self_);
 
   TimingLogger::ScopedSplit split("MarkingPhase", &timings_);
@@ -762,18 +783,34 @@
   if (generational_) {
     // Decide whether to do a whole heap collection or a bump pointer
     // only space collection at the next collection by updating
-    // whole_heap_collection. Enable whole_heap_collection once every
-    // kDefaultWholeHeapCollectionInterval collections.
+    // whole_heap_collection.
     if (!whole_heap_collection_) {
-      --whole_heap_collection_interval_counter_;
-      DCHECK_GE(whole_heap_collection_interval_counter_, 0);
-      if (whole_heap_collection_interval_counter_ == 0) {
-        whole_heap_collection_ = true;
+      if (!kUseBytesPromoted) {
+        // Enable whole_heap_collection once every
+        // kDefaultWholeHeapCollectionInterval collections.
+        --whole_heap_collection_interval_counter_;
+        DCHECK_GE(whole_heap_collection_interval_counter_, 0);
+        if (whole_heap_collection_interval_counter_ == 0) {
+          whole_heap_collection_ = true;
+        }
+      } else {
+        // Enable whole_heap_collection if the bytes promoted since
+        // the last whole heap collection exceeds a threshold.
+        bytes_promoted_since_last_whole_heap_collection_ += bytes_promoted_;
+        if (bytes_promoted_since_last_whole_heap_collection_ >= kBytesPromotedThreshold) {
+          whole_heap_collection_ = true;
+        }
       }
     } else {
-      DCHECK_EQ(whole_heap_collection_interval_counter_, 0);
-      whole_heap_collection_interval_counter_ = kDefaultWholeHeapCollectionInterval;
-      whole_heap_collection_ = false;
+      if (!kUseBytesPromoted) {
+        DCHECK_EQ(whole_heap_collection_interval_counter_, 0);
+        whole_heap_collection_interval_counter_ = kDefaultWholeHeapCollectionInterval;
+        whole_heap_collection_ = false;
+      } else {
+        // Reset it.
+        bytes_promoted_since_last_whole_heap_collection_ = bytes_promoted_;
+        whole_heap_collection_ = false;
+      }
     }
   }
   // Clear all of the spaces' mark bitmaps.
diff --git a/runtime/gc/collector/semi_space.h b/runtime/gc/collector/semi_space.h
index f067cb2..3442751 100644
--- a/runtime/gc/collector/semi_space.h
+++ b/runtime/gc/collector/semi_space.h
@@ -217,6 +217,11 @@
   // bump pointer space to the non-moving space.
   uint64_t bytes_promoted_;
 
+  // Used for the generational mode. Keeps track of how many bytes of
+  // objects have been copied so far from the bump pointer space to
+  // the non-moving space, since the last whole heap collection.
+  uint64_t bytes_promoted_since_last_whole_heap_collection_;
+
   // Used for the generational mode. When true, collect the whole
   // heap. When false, collect only the bump pointer spaces.
   bool whole_heap_collection_;
@@ -228,6 +233,9 @@
   // How many bytes we avoided dirtying.
   size_t saved_bytes_;
 
+  // The name of the collector.
+  std::string collector_name_;
+
   // Used for the generational mode. The default interval of the whole
   // heap collection. If N, the whole heap collection occurs every N
   // collections.
diff --git a/runtime/gc/heap.cc b/runtime/gc/heap.cc
index 915e54f..daf0fb3 100644
--- a/runtime/gc/heap.cc
+++ b/runtime/gc/heap.cc
@@ -326,7 +326,8 @@
   if (kMovingCollector) {
     // TODO: Clean this up.
     bool generational = post_zygote_collector_type_ == kCollectorTypeGSS;
-    semi_space_collector_ = new collector::SemiSpace(this, generational);
+    semi_space_collector_ = new collector::SemiSpace(this, generational,
+                                                     generational ? "generational" : "");
     garbage_collectors_.push_back(semi_space_collector_);
 
     concurrent_copying_collector_ = new collector::ConcurrentCopying(this);
@@ -1859,9 +1860,6 @@
       << "Could not find garbage collector with collector_type="
       << static_cast<size_t>(collector_type_) << " and gc_type=" << gc_type;
   ATRACE_BEGIN(StringPrintf("%s %s GC", PrettyCause(gc_cause), collector->GetName()).c_str());
-  if (!clear_soft_references) {
-    clear_soft_references = gc_type != collector::kGcTypeSticky;  // TODO: GSS?
-  }
   collector->Run(gc_cause, clear_soft_references || runtime->IsZygote());
   total_objects_freed_ever_ += collector->GetFreedObjects();
   total_bytes_freed_ever_ += collector->GetFreedBytes();