Bug 633986 Pref nice value, default to 1 on Android r=dougt a=blocking-fennec

dom/ipc/ContentChild.cpp

@@ -88,14 +88,6 @@
 #include "nsPermissionManager.h"
 #endif
 
-#if defined(ANDROID) || defined(LINUX)
-#include <sys/time.h>
-#include <sys/resource.h>
-// TODO: For other platforms that support setpriority, figure out
-//       appropriate values of niceness
-static const int kRelativeNiceness = 10;
-#endif
-
 #include "nsAccelerometer.h"
 
 #if defined(ANDROID)
@@ -233,18 +225,6 @@ ContentChild::Init(MessageLoop* aIOLoop,
 
     NS_ASSERTION(!sSingleton, "only one ContentChild per child");
 
-#if defined(ANDROID) || defined(LINUX)
-    // XXX We change the behavior of Linux child processes here. That
-    // means that, not just in Fennec, but also in Firefox, once it has
-    // child processes, those will be niced. IOW, Firefox with child processes
-    // will have different performance profiles on Linux than other
-    // platforms. This may alter Talos results and so forth.
-    char* relativeNicenessStr = getenv("MOZ_CHILD_PROCESS_RELATIVE_NICENESS");
-    setpriority(PRIO_PROCESS, 0, getpriority(PRIO_PROCESS, 0) +
-            (relativeNicenessStr ? atoi(relativeNicenessStr) :
-             kRelativeNiceness));
-#endif
-
     Open(aChannel, aParentHandle, aIOLoop);
     sSingleton = this;
 
@@ -415,7 +395,7 @@ ContentChild::RecvSetOffline(const PRBool& offline)
   NS_ASSERTION(io, "IO Service can not be null");
 
   io->SetOffline(offline);
-    
+
   return true;
 }
 
@@ -435,7 +415,7 @@ ContentChild::ActorDestroy(ActorDestroyReason why)
 #endif
 
     mAlertObservers.Clear();
-    
+
     nsCOMPtr<nsIConsoleService> svc(do_GetService(NS_CONSOLESERVICE_CONTRACTID));
     if (svc) {
         svc->UnregisterListener(mConsoleListener);

dom/ipc/ContentParent.cpp

@@ -70,6 +70,11 @@
 #include "nsConsoleMessage.h"
 #include "AudioParent.h"
 
+#if defined(ANDROID) || defined(LINUX)
+#include <sys/time.h>
+#include <sys/resource.h>
+#endif
+
 #ifdef MOZ_PERMISSIONS
 #include "nsPermissionManager.h"
 #endif
@@ -145,6 +150,26 @@ ContentParent::OnChannelConnected(int32 pid)
     }
     else {
         SetOtherProcess(handle);
+
+#if defined(ANDROID) || defined(LINUX)
+        EnsurePrefService();
+        nsCOMPtr<nsIPrefBranch> branch;
+        branch = do_QueryInterface(mPrefService);
+
+        // Check nice preference
+        PRInt32 nice = 0;
+        branch->GetIntPref("dom.ipc.content.nice", &nice);
+
+        // Environment variable overrides preference
+        char* relativeNicenessStr = getenv("MOZ_CHILD_PROCESS_RELATIVE_NICENESS");
+        if (relativeNicenessStr) {
+            nice = atoi(relativeNicenessStr);
+        }
+
+        if (nice != 0) {
+            setpriority(PRIO_PROCESS, pid, getpriority(PRIO_PROCESS, pid) + nice);
+        }
+#endif
     }
 }