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authorSteven Rostedt <rostedt@goodmis.org>2008-07-09 00:15:32 -0400
committerIngo Molnar <mingo@elte.hu>2008-07-11 15:53:27 +0200
commita83bc47c33ab182f1e48977fd5a04024d713c75e (patch)
tree759eb1afc83271ee2815dbd1214635ec7b506b5c /kernel/sched_clock.c
parentc0c87734f125d2fa8ebc70310f3257fa6209f2b6 (diff)
downloadlinux-stericsson-a83bc47c33ab182f1e48977fd5a04024d713c75e.tar.gz
sched_clock: record TSC after gtod
To read the gtod we need to grab the xtime lock for read. Reading the gtod before the TSC can cause a bigger gab if the xtime lock is contended. This patch simply reverses the order to read the TSC after the gtod. The locking in the reading of the gtod handles any barriers one might think is needed. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Cc: Steven Rostedt <srostedt@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: john stultz <johnstul@us.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/sched_clock.c')
-rw-r--r--kernel/sched_clock.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
index ee7cce5029ce..28ff6bf5e02b 100644
--- a/kernel/sched_clock.c
+++ b/kernel/sched_clock.c
@@ -237,8 +237,8 @@ void sched_clock_tick(void)
WARN_ON_ONCE(!irqs_disabled());
- now = sched_clock();
now_gtod = ktime_to_ns(ktime_get());
+ now = sched_clock();
__raw_spin_lock(&scd->lock);
__update_sched_clock(scd, now, NULL);