1 files changed, 20 insertions, 22 deletions
diff --git a/libcutils/sched_policy.c b/libcutils/sched_policy.c
index d20d217..d3cedd4 100644
--- a/libcutils/sched_policy.c
+++ b/libcutils/sched_policy.c
@@ -1,6 +1,4 @@
-
-/* libs/cutils/sched_policy.c
-**
+/*
 ** Copyright 2007, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License"); 
@@ -18,14 +16,17 @@
 
 #define LOG_TAG "SchedPolicy"
 
+#include <errno.h>
+#include <fcntl.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <string.h>
-#include <errno.h>
-#include <fcntl.h>
+#include <unistd.h>
+
 #include <cutils/sched_policy.h>
-#include <cutils/log.h>
+#include <log/log.h>
+
+#define UNUSED __attribute__((__unused__))
 
 /* Re-map SP_DEFAULT to the system default policy, and leave other values unchanged.
  * Call this any place a SchedPolicy is used as an input parameter.
@@ -38,21 +39,20 @@ static inline SchedPolicy _policy(SchedPolicy p)
 
 #if defined(HAVE_ANDROID_OS) && defined(HAVE_SCHED_H) && defined(HAVE_PTHREADS)
 
-#include <sched.h>
 #include <pthread.h>
-
-#ifndef SCHED_NORMAL
-  #define SCHED_NORMAL 0
-#endif
-
-#ifndef SCHED_BATCH
-  #define SCHED_BATCH 3
-#endif
+#include <sched.h>
+#include <sys/prctl.h>
 
 #define POLICY_DEBUG 0
 
 #define CAN_SET_SP_SYSTEM 0 // non-zero means to implement set_sched_policy(tid, SP_SYSTEM)
 
+// This prctl is only available in Android kernels.
+#define PR_SET_TIMERSLACK_PID 41
+
+// timer slack value in nS enforced when the thread moves to background
+#define TIMER_SLACK_BG 40000000
+
 static pthread_once_t the_once = PTHREAD_ONCE_INIT;
 
 static int __sys_supports_schedgroups = -1;
@@ -221,11 +221,9 @@ static int getSchedulerGroup(int tid, char* buf, size_t bufLen)
 
 int get_sched_policy(int tid, SchedPolicy *policy)
 {
-#ifdef HAVE_GETTID
     if (tid == 0) {
         tid = gettid();
     }
-#endif
     pthread_once(&the_once, __initialize);
 
     if (__sys_supports_schedgroups) {
@@ -260,11 +258,9 @@ int get_sched_policy(int tid, SchedPolicy *policy)
 
 int set_sched_policy(int tid, SchedPolicy policy)
 {
-#ifdef HAVE_GETTID
     if (tid == 0) {
         tid = gettid();
     }
-#endif
     policy = _policy(policy);
     pthread_once(&the_once, __initialize);
 
@@ -324,6 +320,8 @@ int set_sched_policy(int tid, SchedPolicy policy)
                            &param);
     }
 
+    prctl(PR_SET_TIMERSLACK_PID, policy == SP_BACKGROUND ? TIMER_SLACK_BG : 0, tid);
+
     return 0;
 }
 
@@ -331,12 +329,12 @@ int set_sched_policy(int tid, SchedPolicy policy)
 
 /* Stubs for non-Android targets. */
 
-int set_sched_policy(int tid, SchedPolicy policy)
+int set_sched_policy(int tid UNUSED, SchedPolicy policy UNUSED)
 {
     return 0;
 }
 
-int get_sched_policy(int tid, SchedPolicy *policy)
+int get_sched_policy(int tid UNUSED, SchedPolicy *policy)
 {
     *policy = SP_SYSTEM_DEFAULT;
     return 0;