Re: [PATCH] cputime.h seems to assume HZ==1000

From: Linus Torvalds
Date: Mon Jan 17 2005 - 21:48:29 EST




On Mon, 17 Jan 2005, Roland McGrath wrote:
>
> Shouldn't msecs mean msecs, not secs/HZ?

Hmm, sure, but why go through "msecs" at all?

> --- linux-2.6/include/asm-generic/cputime.h
> +++ linux-2.6/include/asm-generic/cputime.h
> @@ -35,8 +35,8 @@ typedef u64 cputime64_t;
> /*
> * Convert cputime to seconds and back.
> */
> -#define cputime_to_secs(__ct) (jiffies_to_msecs(__ct) / HZ)
> -#define secs_to_cputime(__secs) (msecs_to_jiffies(__secs * HZ))
> +#define cputime_to_secs(__ct) (jiffies_to_msecs(__ct) / 1000)
> +#define secs_to_cputime(__secs) (msecs_to_jiffies(__secs * 1000))

iow, why not

#define cputime_to_secs(jif) ((jif) / HZ)
#define secs_to_cputime(sec) ((sec) * HZ)

which avoids double rounding issues etc.

Not to mention that "secs_to_cputime()" lacks the proper parenthesis.

More signers-off-on-this-thing added.

Linus
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