Re: HZ, preferably as small as possible

Martin Dalecki
2002-07-12T11:59:45Z

Użytkownik Bill Davidsen napisał:
> On Thu, 11 Jul 2002, Martin Dalecki wrote:
>
>
>>vmstat.c:
>>
>>hz = sysconf(_SC_CLK_TCK); /* get ticks/s from system */
>>
>>And yes I know the libproc is *evil* in this area.
>>The rest should be an implementation detail of sysconf().
>
>
> Yes, any of the changes need to make the dynamic value available to
> programs. Alas, too many programs grab the HZ value and compile it in, and
> don't work right on a kernel with a modified rate. I don't know if the
> CLK_TCK macro is dynamic or not, I sure hope so.
>
> I'd like to see it set at boot time, and available in /proc/sys for easy
> use by scripts. As noted by others, there are a lot of uses in the kernel
> source which assume that arithmetic will happen at compile time, and even
> if you ignore the overhead it would take a lot of rewriting to make it
> dynamic. Setting it a boot time gets most of the gain and none of the
> pain (boot time = pick a kernel, not a parameter).
>

IMHO there where reasons why the standards are defining a function
to access this information from applications.