chromium/chrome/browser/performance_manager/policies/working_set_trimmer_policy.h

// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CHROME_BROWSER_PERFORMANCE_MANAGER_POLICIES_WORKING_SET_TRIMMER_POLICY_H_
#define CHROME_BROWSER_PERFORMANCE_MANAGER_POLICIES_WORKING_SET_TRIMMER_POLICY_H_

#include "base/time/time.h"
#include "components/performance_manager/public/graph/graph.h"
#include "components/performance_manager/public/graph/node_attached_data.h"
#include "components/performance_manager/public/graph/node_data_describer.h"
#include "components/performance_manager/public/graph/process_node.h"

namespace performance_manager {
namespace policies {

// Empties the working set of processes in which all frames are frozen.
//
// Objective #1: Track working set growth rate.
//   Swap thrashing occurs when a lot of pages are accessed in a short period of
//   time. Swap thrashing can be reduced by reducing the number of pages
//   accessed by processes in which all frames are frozen. To track efforts
//   towards this goal, we empty the working set of processes when all their
//   frames become frozen and record the size of their working set after x
//   minutes.
//   TODO(fdoray): Record the working set size x minutes after emptying it.
//   https://crbug.com/885293
//
// Objective #2: Improve performance.
//   We hypothesize that emptying the working set of a process causes its pages
//   to be compressed and/or written to disk preemptively, which makes more
//   memory available quickly for foreground processes and improves global
//   browser performance.
class WorkingSetTrimmerPolicy : public GraphOwned,
                                public ProcessNode::ObserverDefaultImpl,
                                public NodeDataDescriberDefaultImpl { … };

}  // namespace policies
}  // namespace performance_manager

#endif  // CHROME_BROWSER_PERFORMANCE_MANAGER_POLICIES_WORKING_SET_TRIMMER_POLICY_H_