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authorThomas Gleixner <tglx@linutronix.de>2013-02-21 22:51:40 +0000
committerJohn Stultz <john.stultz@linaro.org>2013-04-04 13:18:32 -0700
commitca4523cda429712fc135c5db50920d90eb776a6c (patch)
tree6a8c260a24bcd5a188d25790984d0aa5a3fb3428 /kernel/time/timekeeping.c
parent48cdc135d4840aab8efd2fc3bacb5d7dfd94a9c8 (diff)
downloadlinaro-lsk-ca4523cda429712fc135c5db50920d90eb776a6c.tar.gz
timekeeping: Shorten seq_count region
Shorten the seqcount write hold region to the actual update of the timekeeper and the related data (e.g vsyscall). On a contemporary x86 system this reduces the maximum latencies on Preempt-RT from 8us to 4us on the non-timekeeping cores. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'kernel/time/timekeeping.c')
-rw-r--r--kernel/time/timekeeping.c5
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index d20ffdad62e..c4d2a8751f3 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1341,7 +1341,6 @@ static void update_wall_time(void)
unsigned long flags;
raw_spin_lock_irqsave(&timekeeper_lock, flags);
- write_seqcount_begin(&timekeeper_seq);
/* Make sure we're fully resumed: */
if (unlikely(timekeeping_suspended))
@@ -1393,6 +1392,7 @@ static void update_wall_time(void)
*/
accumulate_nsecs_to_secs(tk);
+ write_seqcount_begin(&timekeeper_seq);
/* Update clock->cycle_last with the new value */
clock->cycle_last = tk->cycle_last;
/*
@@ -1407,9 +1407,8 @@ static void update_wall_time(void)
*/
memcpy(real_tk, tk, sizeof(*tk));
timekeeping_update(real_tk, false, false);
-
-out:
write_seqcount_end(&timekeeper_seq);
+out:
raw_spin_unlock_irqrestore(&timekeeper_lock, flags);
}