gpu: Reuse transfer buffers more aggresively

gpu/command_buffer/client/mapped_memory.cc

Index: gpu/command_buffer/client/mapped_memory.cc
diff --git a/gpu/command_buffer/client/mapped_memory.cc b/gpu/command_buffer/client/mapped_memory.cc
index 15584aaaf07daebf1bf20ba5225e086bfc1da4db..890732c916f1b969475802f0df977a2fcce55312 100644
--- a/gpu/command_buffer/client/mapped_memory.cc
+++ b/gpu/command_buffer/client/mapped_memory.cc
@@ -13,19 +13,22 @@
 
 namespace gpu {
 
-MemoryChunk::MemoryChunk(
-    int32 shm_id, gpu::Buffer shm, CommandBufferHelper* helper)
+MemoryChunk::MemoryChunk(int32 shm_id,
+                         gpu::Buffer shm,
+                         bool aggressive_reuse,
+                         CommandBufferHelper* helper)
     : shm_id_(shm_id),
       shm_(shm),
-      allocator_(shm.size, helper, shm.ptr) {
+      allocator_(shm.size, aggressive_reuse, helper, shm.ptr) {
 }
 
 MappedMemoryManager::MappedMemoryManager(CommandBufferHelper* helper,
-                                         size_t unused_memory_reclaim_limit)
+                                         MappedMemoryManagerSettings settings)
     : chunk_size_multiple_(1),
       helper_(helper),
       allocated_memory_(0),
-      max_free_bytes_(unused_memory_reclaim_limit) {
+      max_free_bytes_(settings.unused_memory_reclaim_limit),
+      aggressive_reuse_(settings.aggressive_reuse) {
 }
 
 MappedMemoryManager::~MappedMemoryManager() {
@@ -48,7 +51,10 @@ void* MappedMemoryManager::Alloc(
       MemoryChunk* chunk = chunks_[ii];
       chunk->FreeUnused();
       total_bytes_in_use += chunk->bytes_in_use();
-      if (chunk->GetLargestFreeSizeWithoutWaiting() >= size) {
+      unsigned int largest_size =
+          aggressive_reuse_ ? chunk->GetLargestFreeSizeWithWaiting()
+                            : chunk->GetLargestFreeSizeWithoutWaiting();
+      if (largest_size >= size) {
         void* mem = chunk->Alloc(size);
         DCHECK(mem);
         *shm_id = chunk->shm_id();
@@ -60,7 +66,7 @@ void* MappedMemoryManager::Alloc(
     // If there is a memory limit being enforced and total free
     // memory (allocated_memory_ - total_bytes_in_use) is larger than
     // the limit try waiting.
-    if (max_free_bytes_ != kNoLimit &&
+    if (!aggressive_reuse_ && max_free_bytes_ != kNoLimit &&
         (allocated_memory_ - total_bytes_in_use) >= max_free_bytes_) {
       TRACE_EVENT0("gpu", "MappedMemoryManager::Alloc::wait");
       for (size_t ii = 0; ii < chunks_.size(); ++ii) {
@@ -85,7 +91,7 @@ void* MappedMemoryManager::Alloc(
   gpu::Buffer shm = cmd_buf->CreateTransferBuffer(chunk_size, &id);
   if (id  < 0)
     return NULL;
-  MemoryChunk* mc = new MemoryChunk(id, shm, helper_);
+  MemoryChunk* mc = new MemoryChunk(id, shm, aggressive_reuse_, helper_);
   allocated_memory_ += mc->GetSize();
   chunks_.push_back(mc);
   void* mem = mc->Alloc(size);