sched: sched_clock_cpu() based cpu_clock()

with sched_clock_cpu() being reasonably in sync between cpus (max 1 jiffy
difference) use this to provide cpu_clock().

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 12 insertions, 0 deletions

diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index ce05271219a..3c696db5945 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -244,3 +244,15 @@ unsigned long long __attribute__((weak)) sched_clock(void)
 {
 	return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
 }
+
+unsigned long long cpu_clock(int cpu)
+{
+	unsigned long long clock;
+	unsigned long flags;
+
+	raw_local_irq_save(flags);
+	clock = sched_clock_cpu(cpu);
+	raw_local_irq_restore(flags);
+
+	return clock;
+}