From d34fac541a5a541b4207ee9cdbcc5005b5fa848c Mon Sep 17 00:00:00 2001
From: Isaac Chen <ycchen@google.com>
Date: Thu, 16 Feb 2017 11:51:08 +0800
Subject: [PATCH] Turned ENABLE_CPUSETS into runtime decision.

ENABLE_CPUSETS is usually set in BoardConfig.mk to use CONFIG_CPUSETS
feature of Linux kernel.

This change turns the build time variable into runtime decision by
checking if a special file, "tasks", can be found under the mount
point, /dev/cpuset, for cpusets.

Bug: 34726944

Test: Tested on Sailfish
          without cpuset mounted
	  with cpuset mounted, but without schedtune mounted
	  with cpuset mounted and with schedtune mounted

Change-Id: I1c044c3c9d4d15360a1605e7022da84d94df4014
---
 core/jni/android_util_Process.cpp | 58 +++++++++++++++----------------
 1 file changed, 28 insertions(+), 30 deletions(-)

diff --git a/core/jni/android_util_Process.cpp b/core/jni/android_util_Process.cpp
index b57f2362a2846..a03d3c503e1c3 100644
--- a/core/jni/android_util_Process.cpp
+++ b/core/jni/android_util_Process.cpp
@@ -252,25 +252,26 @@ void android_os_Process_setProcessGroup(JNIEnv* env, jobject clazz, int pid, jin
             if (t_pri >= ANDROID_PRIORITY_BACKGROUND) {
                 // This task wants to stay at background
                 // update its cpuset so it doesn't only run on bg core(s)
-#ifdef ENABLE_CPUSETS
-                int err = set_cpuset_policy(t_pid, sp);
-                if (err != NO_ERROR) {
-                    signalExceptionForGroupError(env, -err, t_pid);
-                    break;
+                if (cpusets_enabled()) {
+                    int err = set_cpuset_policy(t_pid, sp);
+                    if (err != NO_ERROR) {
+                        signalExceptionForGroupError(env, -err, t_pid);
+                        break;
+                    }
                 }
-#endif
                 continue;
             }
         }
         int err;
-#ifdef ENABLE_CPUSETS
-        // set both cpuset and cgroup for general threads
-        err = set_cpuset_policy(t_pid, sp);
-        if (err != NO_ERROR) {
-            signalExceptionForGroupError(env, -err, t_pid);
-            break;
+
+        if (cpusets_enabled()) {
+            // set both cpuset and cgroup for general threads
+            err = set_cpuset_policy(t_pid, sp);
+            if (err != NO_ERROR) {
+                signalExceptionForGroupError(env, -err, t_pid);
+                break;
+            }
         }
-#endif
 
         err = set_sched_policy(t_pid, sp);
         if (err != NO_ERROR) {
@@ -291,7 +292,6 @@ jint android_os_Process_getProcessGroup(JNIEnv* env, jobject clazz, jint pid)
     return (int) sp;
 }
 
-#ifdef ENABLE_CPUSETS
 /** Sample CPUset list format:
  *  0-3,4,6-8
  */
@@ -367,7 +367,6 @@ static void get_cpuset_cores_for_policy(SchedPolicy policy, cpu_set_t *cpu_set)
     }
     return;
 }
-#endif
 
 
 /**
@@ -376,22 +375,21 @@ static void get_cpuset_cores_for_policy(SchedPolicy policy, cpu_set_t *cpu_set)
  * them in the passed in cpu_set_t
  */
 void get_exclusive_cpuset_cores(SchedPolicy policy, cpu_set_t *cpu_set) {
-#ifdef ENABLE_CPUSETS
-    int i;
-    cpu_set_t tmp_set;
-    get_cpuset_cores_for_policy(policy, cpu_set);
-    for (i = 0; i < SP_CNT; i++) {
-        if ((SchedPolicy) i == policy) continue;
-        get_cpuset_cores_for_policy((SchedPolicy)i, &tmp_set);
-        // First get cores exclusive to one set or the other
-        CPU_XOR(&tmp_set, cpu_set, &tmp_set);
-        // Then get the ones only in cpu_set
-        CPU_AND(cpu_set, cpu_set, &tmp_set);
+    if (cpusets_enabled()) {
+        int i;
+        cpu_set_t tmp_set;
+        get_cpuset_cores_for_policy(policy, cpu_set);
+        for (i = 0; i < SP_CNT; i++) {
+            if ((SchedPolicy) i == policy) continue;
+            get_cpuset_cores_for_policy((SchedPolicy)i, &tmp_set);
+            // First get cores exclusive to one set or the other
+            CPU_XOR(&tmp_set, cpu_set, &tmp_set);
+            // Then get the ones only in cpu_set
+            CPU_AND(cpu_set, cpu_set, &tmp_set);
+        }
+    } else {
+        CPU_ZERO(cpu_set);
     }
-#else
-    (void) policy;
-    CPU_ZERO(cpu_set);
-#endif
     return;
 }