Re: [PATCH] fix for sched_clock() when using jiffies

Andrew Morton
2009-05-08T23:05:23Z

On Sat, 9 May 2009 05:34:44 +0930
Ron <ron@debian.org> wrote:

>
> Account for the initial offset to the jiffy count.
>
> Signed-off-by: Ron Lee <ron@debian.org>
>
> ---
> kernel/sched_clock.c | 3 ++-
> 1 files changed, 2 insertions(+), 1 deletions(-)
>
> diff --git a/kernel/sched_clock.c b/kernel/sched_clock.c
> index a0b0852..a1567b1 100644
> --- a/kernel/sched_clock.c
> +++ b/kernel/sched_clock.c
> @@ -37,7 +37,8 @@
> */
> unsigned long long __attribute__((weak)) sched_clock(void)
> {
> - return (unsigned long long)jiffies * (NSEC_PER_SEC / HZ);
> + return (unsigned long long)(jiffies - INITIAL_JIFFIES)
> + * (NSEC_PER_SEC / HZ);
> }
>
> static __read_mostly int sched_clock_running;

Why? I assume that you encountered some problem which was fixed
by this patch. What was that problem?