[aw] Add SetCpuAffinityToLittleCores method

Add a method in AwDebug to set CPU affinity to little cores in WebView.

Bug: 1111789
Change-Id: Iece9bd27d60ec0338da88abf6a69c59dc4268e6f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2521612Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Oksana Zhuravlova <oksamyt@chromium.org>
Reviewed-by: Avi Drissman <avi@chromium.org>
Reviewed-by: Ken Buchanan <kenrb@chromium.org>
Reviewed-by: Eric Seckler <eseckler@chromium.org>
Commit-Queue: Laís Minchillo <laisminchillo@chromium.org>
Auto-Submit: Laís Minchillo <laisminchillo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#826893}

android_webview/browser/aw_debug.cc

@@ -2,14 +2,50 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "android_webview/browser/aw_render_process.h"
 #include "android_webview/browser_jni_headers/AwDebug_jni.h"
 #include "android_webview/common/crash_reporter/crash_keys.h"
 #include "base/android/jni_android.h"
 #include "base/android/jni_string.h"
+#include "base/no_destructor.h"
 #include "components/crash/core/common/crash_key.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/render_process_host_creation_observer.h"
+
+using content::RenderProcessHost;
 
 namespace android_webview {
 
+class AwDebugCpuAffinity : public content::RenderProcessHostCreationObserver {
+ public:
+  AwDebugCpuAffinity() {
+    for (RenderProcessHost::iterator i(RenderProcessHost::AllHostsIterator());
+         !i.IsAtEnd(); i.Advance()) {
+      RenderProcessHost* process_host = i.GetCurrentValue();
+      if (process_host) {
+        SetAffinityForProcessHost(process_host);
+      }
+    }
+  }
+
+  // content::RenderProcessHostCreationObserver:
+  void OnRenderProcessHostCreated(RenderProcessHost* process_host) override {
+    SetAffinityForProcessHost(process_host);
+  }
+
+ private:
+  void SetAffinityForProcessHost(RenderProcessHost* process_host) {
+    process_host->PostTaskWhenProcessIsReady(base::BindOnce(
+        &AwRenderProcess::SetCpuAffinityToLittleCores,
+        base::Unretained(
+            AwRenderProcess::GetInstanceForRenderProcessHost(process_host))));
+  }
+};
+
+static void JNI_AwDebug_SetCpuAffinityToLittleCores(JNIEnv* env) {
+  static base::NoDestructor<AwDebugCpuAffinity> aw_debug_cpu_affinity;
+}
+
 static void JNI_AwDebug_SetSupportLibraryWebkitVersionCrashKey(
     JNIEnv* env,
     const base::android::JavaParamRef<jstring>& version) {

android_webview/browser/aw_render_process.cc

@@ -66,6 +66,10 @@ void AwRenderProcess::SetJsOnlineProperty(bool network_up) {
   renderer_remote_->SetJsOnlineProperty(network_up);
 }
 
+void AwRenderProcess::SetCpuAffinityToLittleCores() {
+  renderer_remote_->SetCpuAffinityToLittleCores();
+}
+
 void AwRenderProcess::Ready() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
 

android_webview/browser/aw_render_process.h

@@ -34,6 +34,7 @@ class AwRenderProcess : public content::RenderProcessHostObserver,
 
   void ClearCache();
   void SetJsOnlineProperty(bool network_up);
+  void SetCpuAffinityToLittleCores();
 
  private:
   void Ready();

android_webview/common/mojom/renderer.mojom

@@ -13,4 +13,8 @@ interface Renderer {
 
   // Adjusts the javascript 'online' property value.
   SetJsOnlineProperty(bool network_up);
+
+  // Set renderer process CPU affinity to little cores. Temporarily added for an
+  // experiment; to be deleted after its conclusion (https://crbug.com/1111789).
+  SetCpuAffinityToLittleCores();
 };

android_webview/java/src/org/chromium/android_webview/AwDebug.java

@@ -38,8 +38,14 @@ public class AwDebug {
         AwDebugJni.get().setSupportLibraryWebkitVersionCrashKey(version);
     }
 
+    @UsedByReflection("")
+    public static void setCpuAffinityToLittleCores() {
+        AwDebugJni.get().setCpuAffinityToLittleCores();
+    }
+
     @NativeMethods
     interface Natives {
         void setSupportLibraryWebkitVersionCrashKey(String version);
+        void setCpuAffinityToLittleCores();
     }
 }

android_webview/renderer/aw_render_thread_observer.cc

@@ -4,6 +4,7 @@
 
 #include "android_webview/renderer/aw_render_thread_observer.h"
 
+#include "content/public/common/cpu_affinity.h"
 #include "third_party/blink/public/common/associated_interfaces/associated_interface_registry.h"
 #include "third_party/blink/public/platform/web_cache.h"
 #include "third_party/blink/public/platform/web_network_state_notifier.h"
@@ -44,4 +45,8 @@ void AwRenderThreadObserver::SetJsOnlineProperty(bool network_up) {
   blink::WebNetworkStateNotifier::SetOnLine(network_up);
 }
 
+void AwRenderThreadObserver::SetCpuAffinityToLittleCores() {
+  content::EnforceProcessCpuAffinity(base::CpuAffinityMode::kLittleCoresOnly);
+}
+
 }  // namespace android_webview

android_webview/renderer/aw_render_thread_observer.h

@@ -30,6 +30,7 @@ class AwRenderThreadObserver : public content::RenderThreadObserver,
   // mojom::Renderer overrides:
   void ClearCache() override;
   void SetJsOnlineProperty(bool network_up) override;
+  void SetCpuAffinityToLittleCores() override;
 
   void OnRendererAssociatedRequest(
       mojo::PendingAssociatedReceiver<mojom::Renderer> receiver);