sched: add optional support for CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

this replaces the rq->clock stuff (and possibly cpu_clock()).

 - architectures that have an 'imperfect' hardware clock can set
   CONFIG_HAVE_UNSTABLE_SCHED_CLOCK

 - the 'jiffie' window might be superfulous when we update tick_gtod
   before the __update_sched_clock() call in sched_clock_tick()

 - cpu_clock() might be implemented as:

     sched_clock_cpu(smp_processor_id())

   if the accuracy proves good enough - how far can TSC drift in a
   single jiffie when considering the filtering and idle hooks?

[ mingo@elte.hu: various fixes and cleanups ]

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index d99e01f6929a..c863663d204d 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -959,7 +959,7 @@ static void yield_task_fair(struct rq *rq)
                 return;
 
         if (likely(!sysctl_sched_compat_yield) && curr->policy != SCHED_BATCH) {
-                __update_rq_clock(rq);
+                update_rq_clock(rq);
                 /*
                  * Update run-time statistics of the 'current'.
                  */