Record swap metrics

content/browser/memory/swap_metrics_observer_linux.cc

+// Copyright 2017 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/browser/memory/swap_metrics_observer_linux.h"
+
+#include "base/metrics/histogram_macros.h"
+#include "base/process/process_metrics.h"
+
+namespace content {
+
+namespace {
+
+bool HasSwap() {
+  base::SystemMemoryInfoKB memory_info;
+  if (!base::GetSystemMemoryInfo(&memory_info))
+    return false;
+  return memory_info.swap_total > 0;
+}
+
+}  // namespace
+
+// static
+SwapMetricsObserver* SwapMetricsObserver::GetInstance() {
+  static SwapMetricsObserverLinux* instance =
+      HasSwap() ? new SwapMetricsObserverLinux() : nullptr;
+  return instance;
+}
+
+SwapMetricsObserverLinux::SwapMetricsObserverLinux() {}
+
+SwapMetricsObserverLinux::~SwapMetricsObserverLinux() {}
+
+void SwapMetricsObserverLinux::UpdateMetricsInternal(base::TimeDelta interval) {
+  base::SystemMemoryInfoKB memory_info;
+  if (!base::GetSystemMemoryInfo(&memory_info)) {
+    Stop();
+    return;
+  }
+
+  double in_counts = memory_info.pswpin - last_pswpin_;
+  double out_counts = memory_info.pswpout - last_pswpout_;
+  last_pswpin_ = memory_info.pswpin;
+  last_pswpout_ = memory_info.pswpout;
+
+  if (interval.is_zero())
+    return;
+
+  UMA_HISTOGRAM_COUNTS_10000("Memory.Experimental.SwapInPerSecond",
+                             in_counts / interval.InSecondsF());
+  UMA_HISTOGRAM_COUNTS_10000("Memory.Experimental.SwapOutPerSecond",
+                             out_counts / interval.InSecondsF());
+}
+
+}  // namespace content