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SubjectRe: [PATCH] simplify update_times (avoid jiffies/jiffies_64 aliasing problem)
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>>>>> On Thu, 02 Mar 2006 23:02:27 +0900 (JST), Atsushi Nemoto <anemo@mba.ocn.ne.jp> said:
anemo> In kernel 2.6, update_times() is called directly in timer
anemo> interrupt, so there is no point calculating ticks here. This
anemo> also get rid of difference of jiffies and jiffies_64 due to
anemo> compiler's optimization (which was reported previously with
anemo> subject "jiffies_64 vs. jiffies").

Sorry, it seems the patch breaks lost-tick handling on x86_64. Here
is a revised patch including its adjustment.


In kernel 2.6, update_times() is called directly in timer interrupt,
so there is no point calculating ticks here. This also get rid of
difference of jiffies and jiffies_64 due to compiler's optimization
(which was reported previously with subject "jiffies_64 vs. jiffies").
Also adjust x86_64 timer interrupt handler with this change.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>

diff --git a/arch/x86_64/kernel/time.c b/arch/x86_64/kernel/time.c
index 3080f84..7a1d790 100644
--- a/arch/x86_64/kernel/time.c
+++ b/arch/x86_64/kernel/time.c
@@ -423,7 +423,8 @@ void main_timer_handler(struct pt_regs *

if (lost > 0) {
handle_lost_ticks(lost, regs);
- jiffies += lost;
+ while (lost--)
+ do_timer(regs);
}

/*
diff --git a/kernel/timer.c b/kernel/timer.c
index fe3a9a9..6188c99 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -906,14 +906,9 @@ void run_local_timers(void)
*/
static inline void update_times(void)
{
- unsigned long ticks;
-
- ticks = jiffies - wall_jiffies;
- if (ticks) {
- wall_jiffies += ticks;
- update_wall_time(ticks);
- }
- calc_load(ticks);
+ wall_jiffies++;
+ update_wall_time(1);
+ calc_load(1);
}

/*
-
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