sched: add [__]update_rq_clock(rq)

[Linux Kernel Mailing List]

Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=b04a0f4c1651a553ee1a03dc70297d66ec74db5c
Commit:     b04a0f4c1651a553ee1a03dc70297d66ec74db5c
Parent:     a4ac01c36e286dd1b9a1d5cd7422c5af51dc55f8
Author:     Ingo Molnar <[EMAIL PROTECTED]>
AuthorDate: Thu Aug 9 11:16:46 2007 +0200
Committer:  Ingo Molnar <[EMAIL PROTECTED]>
CommitDate: Thu Aug 9 11:16:46 2007 +0200

    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 <[EMAIL PROTECTED]>
---
 kernel/sched.c |   30 ++++++++++++++++++++++--------
 1 files changed, 22 insertions(+), 8 deletions(-)

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 @@ static inline int cpu_of(struct rq *rq)
 }
 
 /*
- * 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:
         */
@@ -349,17 +353,24 @@ static unsigned long long __rq_clock(struct rq *rq)
 
        rq->prev_clock_raw = now;
        rq->clock = clock;
+}
 
-       return clock;
+static void update_rq_clock(struct rq *rq)
+{
+       if (likely(smp_processor_id() == cpu_of(rq)))
+               __update_rq_clock(rq);
 }
 
-static unsigned long long rq_clock(struct rq *rq)
+static u64 __rq_clock(struct rq *rq)
 {
-       int this_cpu = smp_processor_id();
+       __update_rq_clock(rq);
 
-       if (this_cpu == cpu_of(rq))
-               return __rq_clock(rq);
+       return rq->clock;
+}
 
+static u64 rq_clock(struct rq *rq)
+{
+       update_rq_clock(rq);
        return rq->clock;
 }
 
@@ -386,9 +397,12 @@ unsigned long long cpu_clock(int cpu)
 {
        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;
-
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