Improve cpuset support for surfaceflinger.
SurfaceFlinger needs some of its threads in the system-background cpuset
and some of its threads (the binder pool) outside of the
system-background cpuset in order to improve UI perf/power
consumption. Remove surfaceflinger from the system-background cpuset in
init.rc and allow a thread to place itself in the system-background
cpuset given enough permissions.
bug 25745866
Change-Id: I85f7e41c5439e6ad7cc2d355e51f5dfb3a0c7088
diff --git a/libcutils/sched_policy.c b/libcutils/sched_policy.c
index 6bba3a7..280a083 100644
--- a/libcutils/sched_policy.c
+++ b/libcutils/sched_policy.c
@@ -62,6 +62,7 @@
#ifdef USE_CPUSETS
// File descriptors open to /dev/cpuset/../tasks, setup by initialize, or -1 on error
+static int system_bg_cpuset_fd = -1;
static int bg_cpuset_fd = -1;
static int fg_cpuset_fd = -1;
static int bg_schedboost_fd = -1;
@@ -130,6 +131,9 @@
fg_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
filename = "/dev/cpuset/background/tasks";
bg_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+ filename = "/dev/cpuset/system-background/tasks";
+ system_bg_cpuset_fd = open(filename, O_WRONLY | O_CLOEXEC);
+
#ifdef USE_SCHEDBOOST
filename = "/sys/fs/cgroup/stune/foreground/tasks";
fg_schedboost_fd = open(filename, O_WRONLY | O_CLOEXEC);
@@ -138,7 +142,6 @@
#endif
}
#endif
-
}
/*
@@ -273,6 +276,10 @@
fd = fg_cpuset_fd;
boost_fd = fg_schedboost_fd;
break;
+ case SP_SYSTEM:
+ fd = system_bg_cpuset_fd;
+ boost_fd = bg_schedboost_fd;
+ break;
default:
boost_fd = fd = -1;
break;
diff --git a/rootdir/init.rc b/rootdir/init.rc
index a839729..1575c10 100644
--- a/rootdir/init.rc
+++ b/rootdir/init.rc
@@ -180,6 +180,10 @@
chown system system /dev/cpuset/foreground/boost/tasks
chown system system /dev/cpuset/background/tasks
chown system system /dev/cpuset/system-background/tasks
+
+ # set system-background to 0775 so SurfaceFlinger can touch it
+ chmod 0775 /dev/cpuset/system-background
+
chmod 0664 /dev/cpuset/foreground/tasks
chmod 0664 /dev/cpuset/foreground/boost/tasks
chmod 0664 /dev/cpuset/background/tasks