AuxXxilium/linux_dsm_epyc7002
1
0
Fork 0
mirror of https://github.com/AuxXxilium/linux_dsm_epyc7002.git synced 2024-11-25 06:30:54 +07:00
Code Issues Actions Packages Projects Releases Wiki Activity

timekeeping: Shorten seq_count region

Browse Source 
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>
This commit is contained in:
Thomas Gleixner 2013-02-21 22:51:40 +00:00 committed by John Stultz
parent 48cdc135d4
commit ca4523cda4
1 changed files with 2 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
kernel/time/timekeeping.c
View File

@ -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);
}