Estimate freed memory in killing a process faster.

Use memory_instrumentation::OSMetrics::FillOSMemoryDump(), which
reads /proc/<pid>/statm, to get private bytes of a process, to avoid
contention with kswapd under heavy memory pressure.

BUG=chromium:872253
TEST=manual
R=cylee@chromium.org, sonnyrao@chromium.org, fdoray@chromium.org

Change-Id: I4d43933a39c3c89d8ebb81e3ccef20277cedb258
Reviewed-on: https://chromium-review.googlesource.com/1212246
Commit-Queue: Chinglin Yu <chinglinyu@chromium.org>
Reviewed-by: François Doray <fdoray@chromium.org>
Reviewed-by: Cheng-Yu Lee <cylee@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592701}

chrome/browser/resource_coordinator/tab_lifecycle_unit.cc

@@ -486,16 +486,7 @@ bool TabLifecycleUnitSource::TabLifecycleUnit::Load() {
 
 int TabLifecycleUnitSource::TabLifecycleUnit::
     GetEstimatedMemoryFreedOnDiscardKB() const {
-#if defined(OS_CHROMEOS)
-  std::unique_ptr<base::ProcessMetrics> process_metrics(
-      base::ProcessMetrics::CreateProcessMetrics(GetProcessHandle()));
-  base::ProcessMetrics::TotalsSummary summary =
-      process_metrics->GetTotalsSummary();
-  return summary.private_clean_kb + summary.private_dirty_kb + summary.swap_kb;
-#else
-  // TODO(fdoray): Implement this. https://crbug.com/775644
-  return 0;
-#endif
+  return GetPrivateMemoryKB(GetProcessHandle());
 }
 
 bool TabLifecycleUnitSource::TabLifecycleUnit::CanPurge() const {

chrome/browser/resource_coordinator/tab_manager_delegate_chromeos.cc

@@ -31,6 +31,7 @@
 #include "chrome/browser/memory/memory_kills_monitor.h"
 #include "chrome/browser/resource_coordinator/tab_lifecycle_unit_external.h"
 #include "chrome/browser/resource_coordinator/tab_manager_stats_collector.h"
+#include "chrome/browser/resource_coordinator/utils.h"
 #include "chrome/browser/ui/browser.h"
 #include "chrome/browser/ui/browser_list.h"
 #include "chrome/browser/ui/browser_window.h"
@@ -248,12 +249,8 @@ int TabManagerDelegate::MemoryStat::TargetMemoryToFreeKB() {
 }
 
 int TabManagerDelegate::MemoryStat::EstimatedMemoryFreedKB(
-    base::ProcessHandle pid) {
-  std::unique_ptr<base::ProcessMetrics> process_metrics(
-      base::ProcessMetrics::CreateProcessMetrics(pid));
-  base::ProcessMetrics::TotalsSummary summary =
-      process_metrics->GetTotalsSummary();
-  return summary.private_clean_kb + summary.private_dirty_kb + summary.swap_kb;
+    base::ProcessHandle handle) {
+  return GetPrivateMemoryKB(handle);
 }
 
 TabManagerDelegate::TabManagerDelegate(

chrome/browser/resource_coordinator/tab_manager_delegate_chromeos.h

@@ -254,8 +254,8 @@ class TabManagerDelegate::MemoryStat {
   // pre-configured low memory margin.
   virtual int TargetMemoryToFreeKB();
 
-  // Returns estimated memory to be freed if the process |pid| is killed.
-  virtual int EstimatedMemoryFreedKB(base::ProcessHandle pid);
+  // Returns estimated memory to be freed if the process |handle| is killed.
+  virtual int EstimatedMemoryFreedKB(base::ProcessHandle handle);
 
  private:
   // Returns the low memory margin system config. Low memory condition is

chrome/browser/resource_coordinator/utils.cc

@@ -5,6 +5,8 @@
 #include "chrome/browser/resource_coordinator/utils.h"
 
 #include "base/md5.h"
+#include "base/numerics/safe_conversions.h"
+#include "services/resource_coordinator/public/cpp/memory_instrumentation/os_metrics.h"
 
 namespace resource_coordinator {
 
@@ -17,4 +19,26 @@ bool URLShouldBeStoredInLocalDatabase(const GURL& url) {
   return url.SchemeIsHTTPOrHTTPS();
 }
 
+int GetPrivateMemoryKB(base::ProcessHandle handle) {
+  // Private memory footprint of a process is calculated using its private bytes
+  // and swap bytes. ProcessMetrics::GetTotalsSummary() is more precise in
+  // getting the private bytes but can be very slow under heavy memory pressure.
+  // Instead, use anonymous RSS as a faster estimation of private bytes for the
+  // process.
+  auto dump = memory_instrumentation::mojom::RawOSMemDump::New();
+  dump->platform_private_footprint =
+      memory_instrumentation::mojom::PlatformPrivateFootprint::New();
+  bool success = memory_instrumentation::OSMetrics::FillOSMemoryDump(
+      base::GetProcId(handle), dump.get());
+
+  // Failed to get private memory for the process, e.g. the process has died.
+  if (!success)
+    return 0;
+
+  uint64_t total_freed_bytes =
+      dump->platform_private_footprint->rss_anon_bytes +
+      dump->platform_private_footprint->vm_swap_bytes;
+  return base::saturated_cast<int>(total_freed_bytes / 1024);
+}
+
 }  // namespace resource_coordinator

chrome/browser/resource_coordinator/utils.h

@@ -7,6 +7,7 @@
 
 #include <string>
 
+#include "base/process/process_handle.h"
 #include "url/gurl.h"
 #include "url/origin.h"
 
@@ -20,6 +21,9 @@ std::string SerializeOriginIntoDatabaseKey(const url::Origin& origin);
 // database.
 bool URLShouldBeStoredInLocalDatabase(const GURL& url);
 
+// Get the private memory footprint (in KB) for the process.
+int GetPrivateMemoryKB(base::ProcessHandle handle);
+
 }  // namespace resource_coordinator
 
 #endif  // CHROME_BROWSER_RESOURCE_COORDINATOR_UTILS_H_