lkml.org 
[lkml]   [2011]   [Nov]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch 3/7] timekeeping: Make seqcount sections smaller
Move the seqcount bump inside of do_timer() and remove it from
sections which only need the xtime_lock serialization.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/time/tick-common.c | 2 --
kernel/time/tick-sched.c | 4 ----
kernel/time/timekeeping.c | 4 ++--
3 files changed, 2 insertions(+), 8 deletions(-)

Index: linux-2.6/kernel/time/tick-common.c
===================================================================
--- linux-2.6.orig/kernel/time/tick-common.c
+++ linux-2.6/kernel/time/tick-common.c
@@ -64,13 +64,11 @@ static void tick_periodic(int cpu)
{
if (tick_do_timer_cpu == cpu) {
raw_spin_lock(&xtime_lock);
- write_seqcount_begin(&xtime_seq);

/* Keep track of the next tick event */
tick_next_period = ktime_add(tick_next_period, tick_period);

do_timer(1);
- write_seqcount_end(&xtime_seq);
raw_spin_unlock(&xtime_lock);
}

Index: linux-2.6/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.orig/kernel/time/tick-sched.c
+++ linux-2.6/kernel/time/tick-sched.c
@@ -57,7 +57,6 @@ static void tick_do_update_jiffies64(kti

/* Reevalute with xtime_lock held */
raw_spin_lock(&xtime_lock);
- write_seqcount_begin(&xtime_seq);

delta = ktime_sub(now, last_jiffies_update);
if (delta.tv64 >= tick_period.tv64) {
@@ -80,7 +79,6 @@ static void tick_do_update_jiffies64(kti
/* Keep the tick_next_period variable up to date */
tick_next_period = ktime_add(last_jiffies_update, tick_period);
}
- write_seqcount_end(&xtime_seq);
raw_spin_unlock(&xtime_lock);
}

@@ -92,12 +90,10 @@ static ktime_t tick_init_jiffy_update(vo
ktime_t period;

raw_spin_lock(&xtime_lock);
- write_seqcount_begin(&xtime_seq);
/* Did we start the jiffies update yet ? */
if (last_jiffies_update.tv64 == 0)
last_jiffies_update = tick_next_period;
period = last_jiffies_update;
- write_seqcount_end(&xtime_seq);
raw_spin_unlock(&xtime_lock);
return period;
}
Index: linux-2.6/kernel/time/timekeeping.c
===================================================================
--- linux-2.6.orig/kernel/time/timekeeping.c
+++ linux-2.6/kernel/time/timekeeping.c
@@ -1116,8 +1116,10 @@ struct timespec get_monotonic_coarse(voi
*/
void do_timer(unsigned long ticks)
{
+ write_seqcount_begin(&xtime_seq);
jiffies_64 += ticks;
update_wall_time();
+ write_seqcount_end(&xtime_seq);
calc_global_load(ticks);
}

@@ -1165,8 +1167,6 @@ ktime_t ktime_get_monotonic_offset(void)
void xtime_update(unsigned long ticks)
{
raw_spin_lock(&xtime_lock);
- write_seqcount_begin(&xtime_seq);
do_timer(ticks);
- write_seqcount_end(&xtime_seq);
raw_spin_unlock(&xtime_lock);
}



\
 
 \ /
  Last update: 2011-11-14 00:21    [from the cache]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and my Meterkast|Read the blog