sched: add [__]update_rq_clock(rq)
add the [__]update_rq_clock(rq) functions. (No change in functionality,
just reorganization to prepare for elimination of the heavy 64-bit
timestamp-passing in the scheduler.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/sched.c b/kernel/sched.c
index 1fa07c1..d613723 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -318,15 +318,19 @@
}
/*
- * Per-runqueue clock, as finegrained as the platform can give us:
+ * Update the per-runqueue clock, as finegrained as the platform can give
+ * us, but without assuming monotonicity, etc.:
*/
-static unsigned long long __rq_clock(struct rq *rq)
+static void __update_rq_clock(struct rq *rq)
{
u64 prev_raw = rq->prev_clock_raw;
u64 now = sched_clock();
s64 delta = now - prev_raw;
u64 clock = rq->clock;
+#ifdef CONFIG_SCHED_DEBUG
+ WARN_ON_ONCE(cpu_of(rq) != smp_processor_id());
+#endif
/*
* Protect against sched_clock() occasionally going backwards:
*/
@@ -349,20 +353,27 @@
rq->prev_clock_raw = now;
rq->clock = clock;
-
- return clock;
}
-static unsigned long long rq_clock(struct rq *rq)
+static void update_rq_clock(struct rq *rq)
{
- int this_cpu = smp_processor_id();
+ if (likely(smp_processor_id() == cpu_of(rq)))
+ __update_rq_clock(rq);
+}
- if (this_cpu == cpu_of(rq))
- return __rq_clock(rq);
+static u64 __rq_clock(struct rq *rq)
+{
+ __update_rq_clock(rq);
return rq->clock;
}
+static u64 rq_clock(struct rq *rq)
+{
+ update_rq_clock(rq);
+ return rq->clock;
+}
+
/*
* The domain tree (rq->sd) is protected by RCU's quiescent state transition.
* See detach_destroy_domains: synchronize_sched for details.
@@ -386,9 +397,12 @@
{
unsigned long long now;
unsigned long flags;
+ struct rq *rq;
local_irq_save(flags);
- now = rq_clock(cpu_rq(cpu));
+ rq = cpu_rq(cpu);
+ update_rq_clock(rq);
+ now = rq->clock;
local_irq_restore(flags);
return now;