Set cpuset from surfaceflinger.

SurfaceFlinger shouldn't be limited to little cores exclusively, as the
binder threads should be placed on big cores when they are in the
critical path for a RenderThread.

bug 25745866

Change-Id: I9fb65f6d951733f91b4735ff27018411b58b2bfb
diff --git a/services/surfaceflinger/main_surfaceflinger.cpp b/services/surfaceflinger/main_surfaceflinger.cpp
index ca81aaa..4cd7aeb 100644
--- a/services/surfaceflinger/main_surfaceflinger.cpp
+++ b/services/surfaceflinger/main_surfaceflinger.cpp
@@ -42,6 +42,13 @@
 
     set_sched_policy(0, SP_FOREGROUND);
 
+#ifdef ENABLE_CPUSETS
+    // Put most SurfaceFlinger threads in the system-background cpuset
+    // Keeps us from unnecessarily using big cores
+    // Do this after the binder thread pool init
+    set_cpuset_policy(0, SP_SYSTEM);
+#endif
+
     // initialize before clients can connect
     flinger->init();