Move discardable memory to //components from //content

content/common/discardable_shared_memory_heap_perftest.cc

-// Copyright 2015 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 "content/common/discardable_shared_memory_heap.h"
-
-#include <stddef.h>
-#include <algorithm>
-#include <cmath>
-#include <cstdlib>
-#include <utility>
-
-#include "base/bind.h"
-#include "base/callback_helpers.h"
-#include "base/memory/discardable_shared_memory.h"
-#include "base/memory/scoped_vector.h"
-#include "base/process/process_metrics.h"
-#include "testing/gtest/include/gtest/gtest.h"
-#include "testing/perf/perf_test.h"
-
-namespace content {
-namespace {
-
-const int kTimeLimitMs = 2000;
-const int kTimeCheckInterval = 8192;
-
-void NullTask() {
-}
-
-TEST(DiscardableSharedMemoryHeapTest, SearchFreeLists) {
-  size_t block_size = base::GetPageSize();
-  DiscardableSharedMemoryHeap heap(block_size);
-
-  const size_t kBlocks = 4096;
-  const size_t kSegments = 16;
-  size_t segment_size = block_size * kBlocks;
-  int next_discardable_shared_memory_id = 0;
-
-  for (size_t i = 0; i < kSegments; ++i) {
-    std::unique_ptr<base::DiscardableSharedMemory> memory(
-        new base::DiscardableSharedMemory);
-    ASSERT_TRUE(memory->CreateAndMap(segment_size));
-    heap.MergeIntoFreeLists(heap.Grow(std::move(memory), segment_size,
-                                      next_discardable_shared_memory_id++,
-                                      base::Bind(NullTask)));
-  }
-
-  unsigned kSeed = 1;
-  // Use kSeed as seed for random number generator.
-  srand(kSeed);
-
-  // Pre-compute random values.
-  int random_span[kTimeCheckInterval];
-  size_t random_blocks[kTimeCheckInterval];
-  for (int i = 0; i < kTimeCheckInterval; ++i) {
-    random_span[i] = std::rand();
-    // Exponentially distributed block size.
-    const double kLambda = 2.0;
-    double v = static_cast<double>(std::rand()) / RAND_MAX;
-    random_blocks[i] = 1 + log(1.0 - v) / -kLambda * kBlocks;
-  }
-
-  ScopedVector<base::ScopedClosureRunner> spans;
-
-  base::TimeTicks start = base::TimeTicks::Now();
-  base::TimeTicks end = start + base::TimeDelta::FromMilliseconds(kTimeLimitMs);
-  base::TimeDelta accumulator;
-  int count = 0;
-  while (start < end) {
-    for (int i = 0; i < kTimeCheckInterval; ++i) {
-      // Search for a perfect fit if greater than kBlocks.
-      size_t slack =
-          random_blocks[i] < kBlocks ? kBlocks - random_blocks[i] : 0;
-      std::unique_ptr<DiscardableSharedMemoryHeap::Span> span =
-          heap.SearchFreeLists(random_blocks[i], slack);
-      if (span) {
-        spans.push_back(new base::ScopedClosureRunner(
-            base::Bind(&DiscardableSharedMemoryHeap::MergeIntoFreeLists,
-                       base::Unretained(&heap), base::Passed(&span))));
-      } else if (!spans.empty()) {
-        // Merge a random span back into the free list.
-        std::swap(spans[random_span[i] % spans.size()], spans.back());
-        spans.pop_back();
-      }
-
-      ++count;
-    }
-
-    base::TimeTicks now = base::TimeTicks::Now();
-    accumulator += now - start;
-    start = now;
-  }
-
-  spans.clear();
-
-  perf_test::PrintResult("search_free_list", "", "",
-                         count / accumulator.InSecondsF(), "runs/s", true);
-}
-
-}  // namespace
-}  // namespace content