Merge branch 'master'

[pandora-kernel.git] / kernel / timer.c

diff --git a/kernel/timer.c b/kernel/timer.c
index 1433d87..6a2e5f8 100644 (file)
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -752,6 +752,15 @@ static void second_overflow(void)
     else
        time_adj += (time_adj >> 2) + (time_adj >> 5);
 #endif
+#if HZ == 250
+    /* Compensate for (HZ==250) != (1 << SHIFT_HZ).
+     * Add 1.5625% and 0.78125% to get 255.85938; => only 0.05% error (p. 14)
+     */
+    if (time_adj < 0)
+       time_adj -= (-time_adj >> 6) + (-time_adj >> 7);
+    else
+       time_adj += (time_adj >> 6) + (time_adj >> 7);
+#endif
 #if HZ == 1000
     /* Compensate for (HZ==1000) != (1 << SHIFT_HZ).
      * Add 1.5625% and 0.78125% to get 1023.4375; => only 0.05% error (p. 14)
@@ -1151,9 +1160,26 @@ fastcall signed long __sched schedule_timeout(signed long timeout)
  out:
        return timeout < 0 ? 0 : timeout;
 }
-
 EXPORT_SYMBOL(schedule_timeout);
 
+/*
+ * We can use __set_current_state() here because schedule_timeout() calls
+ * schedule() unconditionally.
+ */
+signed long __sched schedule_timeout_interruptible(signed long timeout)
+{
+       __set_current_state(TASK_INTERRUPTIBLE);
+       return schedule_timeout(timeout);
+}
+EXPORT_SYMBOL(schedule_timeout_interruptible);
+
+signed long __sched schedule_timeout_uninterruptible(signed long timeout)
+{
+       __set_current_state(TASK_UNINTERRUPTIBLE);
+       return schedule_timeout(timeout);
+}
+EXPORT_SYMBOL(schedule_timeout_uninterruptible);
+
 /* Thread ID - the internal kernel "pid" */
 asmlinkage long sys_gettid(void)
 {
@@ -1170,8 +1196,7 @@ static long __sched nanosleep_restart(struct restart_block *restart)
        if (!time_after(expire, now))
                return 0;
 
-       current->state = TASK_INTERRUPTIBLE;
-       expire = schedule_timeout(expire - now);
+       expire = schedule_timeout_interruptible(expire - now);
 
        ret = 0;
        if (expire) {
@@ -1199,8 +1224,7 @@ asmlinkage long sys_nanosleep(struct timespec __user *rqtp, struct timespec __us
                return -EINVAL;
 
        expire = timespec_to_jiffies(&t) + (t.tv_sec || t.tv_nsec);
-       current->state = TASK_INTERRUPTIBLE;
-       expire = schedule_timeout(expire);
+       expire = schedule_timeout_interruptible(expire);
 
        ret = 0;
        if (expire) {
@@ -1429,7 +1453,7 @@ static inline u64 time_interpolator_get_cycles(unsigned int src)
        }
 }
 
-static inline u64 time_interpolator_get_counter(void)
+static inline u64 time_interpolator_get_counter(int writelock)
 {
        unsigned int src = time_interpolator->source;
 
@@ -1443,6 +1467,15 @@ static inline u64 time_interpolator_get_counter(void)
                        now = time_interpolator_get_cycles(src);
                        if (lcycle && time_after(lcycle, now))
                                return lcycle;
+
+                       /* When holding the xtime write lock, there's no need
+                        * to add the overhead of the cmpxchg.  Readers are
+                        * force to retry until the write lock is released.
+                        */
+                       if (writelock) {
+                               time_interpolator->last_cycle = now;
+                               return now;
+                       }
                        /* Keep track of the last timer value returned. The use of cmpxchg here
                         * will cause contention in an SMP environment.
                         */
@@ -1456,7 +1489,7 @@ static inline u64 time_interpolator_get_counter(void)
 void time_interpolator_reset(void)
 {
        time_interpolator->offset = 0;
-       time_interpolator->last_counter = time_interpolator_get_counter();
+       time_interpolator->last_counter = time_interpolator_get_counter(1);
 }
 
 #define GET_TI_NSECS(count,i) (((((count) - i->last_counter) & (i)->mask) * (i)->nsec_per_cyc) >> (i)->shift)
@@ -1468,7 +1501,7 @@ unsigned long time_interpolator_get_offset(void)
                return 0;
 
        return time_interpolator->offset +
-               GET_TI_NSECS(time_interpolator_get_counter(), time_interpolator);
+               GET_TI_NSECS(time_interpolator_get_counter(0), time_interpolator);
 }
 
 #define INTERPOLATOR_ADJUST 65536
@@ -1491,7 +1524,7 @@ static void time_interpolator_update(long delta_nsec)
         * and the tuning logic insures that.
          */
 
-       counter = time_interpolator_get_counter();
+       counter = time_interpolator_get_counter(1);
        offset = time_interpolator->offset + GET_TI_NSECS(counter, time_interpolator);
 
        if (delta_nsec < 0 || (unsigned long) delta_nsec < offset)
@@ -1589,10 +1622,8 @@ void msleep(unsigned int msecs)
 {
        unsigned long timeout = msecs_to_jiffies(msecs) + 1;
 
-       while (timeout) {
-               set_current_state(TASK_UNINTERRUPTIBLE);
-               timeout = schedule_timeout(timeout);
-       }
+       while (timeout)
+               timeout = schedule_timeout_uninterruptible(timeout);
 }
 
 EXPORT_SYMBOL(msleep);
@@ -1605,10 +1636,8 @@ unsigned long msleep_interruptible(unsigned int msecs)
 {
        unsigned long timeout = msecs_to_jiffies(msecs) + 1;
 
-       while (timeout && !signal_pending(current)) {
-               set_current_state(TASK_INTERRUPTIBLE);
-               timeout = schedule_timeout(timeout);
-       }
+       while (timeout && !signal_pending(current))
+               timeout = schedule_timeout_interruptible(timeout);
        return jiffies_to_msecs(timeout);
 }