On Fri, 28 Dec 2007 13:26:07 -0800 (PST) Jonathan Lim <[EMAIL PROTECTED]> wrote:
> It's possible that the values used in and returned from jiffies_to_usecs() are
> incorrect because of truncation when variables of type u64 are involved. So a
> function specific to that type is used instead.
>
> Diff'd against: linux/kernel/git/stable/linux-2.6.23.y.git
>
> Signed-off-by: Jonathan Lim <[EMAIL PROTECTED]>
>
> --- a/kernel/tsacct.c 2007-12-28 11:58:05.182065029 -0800
> +++ b/kernel/tsacct.c 2007-12-28 11:57:37.949013675 -0800
> @@ -71,6 +71,17 @@ void bacct_add_tsk(struct taskstats *sta
>
> #ifdef CONFIG_TASK_XACCT
>
> +static inline u64 jiffies_to_usecs_u64(const u64 j)
> +{
> +#if HZ <= USEC_PER_SEC && !(USEC_PER_SEC % HZ)
> + return (USEC_PER_SEC / HZ) * j;
> +#elif HZ > USEC_PER_SEC && !(HZ % USEC_PER_SEC)
> + return (j + (HZ / USEC_PER_SEC) - 1)/(HZ / USEC_PER_SEC);
> +#else
> + return (j * USEC_PER_SEC) / HZ;
> +#endif
> +}
> +
> #define KB 1024
> #define MB (1024*KB)
> /*
> @@ -81,8 +92,8 @@ void xacct_add_tsk(struct taskstats *sta
> struct mm_struct *mm;
>
> /* convert pages-jiffies to Mbyte-usec */
> - stats->coremem = jiffies_to_usecs(p->acct_rss_mem1) * PAGE_SIZE / MB;
> - stats->virtmem = jiffies_to_usecs(p->acct_vm_mem1) * PAGE_SIZE / MB;
> + stats->coremem = jiffies_to_usecs_u64(p->acct_rss_mem1) * PAGE_SIZE /
> MB;
> + stats->virtmem = jiffies_to_usecs_u64(p->acct_vm_mem1) * PAGE_SIZE / MB;
> mm = get_task_mm(p);
> if (mm) {
> /* adjust to KB unit */
Fair enough. But I guess that new function should be a kernel-wide thing
because surely other users will turn up.
Peter has been working on the accuracy of some of these conversion
functions and might need to know about this change?
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