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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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