Commit-ID: ca4523cda429712fc135c5db50920d90eb776a6c Gitweb: http://git.kernel.org/tip/ca4523cda429712fc135c5db50920d90eb776a6c Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Thu, 21 Feb 2013 22:51:40 +0000 Committer: John Stultz <john.stultz@xxxxxxxxxx> CommitDate: Thu, 4 Apr 2013 13:18:32 -0700 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@xxxxxxxxxxxxx> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> --- kernel/time/timekeeping.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index d20ffda..c4d2a87 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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