cc: Use max_bytes_per_copy_operation setting to determine one-copy flush interval.

cc/raster/one_copy_tile_task_worker_pool.cc

 // Copyright 2014 The Chromium 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 "cc/raster/one_copy_tile_task_worker_pool.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/strings/stringprintf.h"
@@ skipping 56 matching lines @@
   ResourceProvider* resource_provider_;
   ResourcePool* resource_pool_;
   const Resource* resource_;
   scoped_ptr<ScopedResource> raster_resource_;
   scoped_ptr<ResourceProvider::ScopedWriteLockGpuMemoryBuffer> lock_;
   CopySequenceNumber sequence_;
 
   DISALLOW_COPY_AND_ASSIGN(RasterBufferImpl);
 };
 
-// Flush interval when performing copy operations.
-const int kCopyFlushPeriod = 4;
-
 // Number of in-flight copy operations to allow.
 const int kMaxCopyOperations = 32;
 
 // Minimum number of rows per copy operation. 4 or greater is required to
 // support compressed texture formats.
 const size_t kMinRowsPerCopyOperation = 4;
 
 // Delay been checking for copy operations to complete.
 const int kCheckForCompletedCopyOperationsTickRateMs = 1;
 
@@ skipping 38 matching lines @@
       task_graph_runner_(task_graph_runner),
       namespace_token_(task_graph_runner->GetNamespaceToken()),
       context_provider_(context_provider),
       resource_provider_(resource_provider),
       resource_pool_(resource_pool),
       max_bytes_per_copy_operation_(max_bytes_per_copy_operation),
       last_issued_copy_operation_(0),
       last_flushed_copy_operation_(0),
       lock_(),
       copy_operation_count_cv_(&lock_),
+      bytes_scheduled_since_last_flush_(0),
       issued_copy_operation_count_(0),
       next_copy_operation_sequence_(1),
       check_for_completed_copy_operations_pending_(false),
       shutdown_(false),
       weak_ptr_factory_(this),
       task_set_finished_weak_ptr_factory_(this) {
   DCHECK(context_provider_);
 }
 
 OneCopyTileTaskWorkerPool::~OneCopyTileTaskWorkerPool() {
@@ skipping 199 matching lines @@
     // released before we can issue a copy.
     pending_copy_operations_.push_back(make_scoped_ptr(
         new CopyOperation(write_lock.Pass(), src, dst,
                           gfx::Rect(0, y, src->size().width(), rows_to_copy))));
 
     y += rows_to_copy;
 
     // Acquire a sequence number for this copy operation.
     sequence = next_copy_operation_sequence_++;
 
+    // Increment |bytes_scheduled_since_last_flush_| by the amount of memory
+    // used for this copy operation.
+    bytes_scheduled_since_last_flush_ += rows_to_copy * bytes_per_row;

[vmpstr, 2015/06/01 18:35:52]

So for big tiles (that are split up into several copies) this would cause us to
possibly post several tasks for the one tile (one per full copy)?

[reveman, 2015/06/04 01:19:51]

Yup, that's the behavior we want.

+
     // Post task that will advance last flushed copy operation to |sequence|
-    // if we have reached the flush period.
-    if ((sequence % kCopyFlushPeriod) == 0) {
+    // when |bytes_scheduled_since_last_flush_| has reached
+    // |max_bytes_per_copy_operation_|.
+    if (bytes_scheduled_since_last_flush_ >= max_bytes_per_copy_operation_) {

[vmpstr, 2015/06/02 23:23:27]

I think you need to DCHECK that max_bytes_per_copy_operation_ is less than
std::numeric_limits<size_t>::max(), since then we would never flush?

Either that or change the layer tree settings default to something smaller.

[reveman, 2015/06/04 01:19:51]

A flush here is not required for correct behavior. numeric_limits<size_t>::max()
should work fine. This flush is just to reduce the size of copy operation
batches sent to the GPU process.

       task_runner_->PostTask(
           FROM_HERE,
           base::Bind(&OneCopyTileTaskWorkerPool::AdvanceLastFlushedCopyTo,
                      weak_ptr_factory_.GetWeakPtr(), sequence));
+      bytes_scheduled_since_last_flush_ = 0;
     }
   }
 
   return sequence;
 }
 
 void OneCopyTileTaskWorkerPool::AdvanceLastIssuedCopyTo(
     CopySequenceNumber sequence) {
   if (last_issued_copy_operation_ >= sequence)
     return;
@@ skipping 139 matching lines @@
                             resource_pool_->total_memory_usage_bytes());
   staging_state->SetInteger("pending_copy_count",
                             resource_pool_->total_resource_count() -
                                 resource_pool_->acquired_resource_count());
   staging_state->SetInteger("bytes_pending_copy",
                             resource_pool_->total_memory_usage_bytes() -
                                 resource_pool_->acquired_memory_usage_bytes());
 }
 
 }  // namespace cc