HEADSUP: HZ=1000 by default on i386

[Poul-Henning Kamp]

In message <xzp7jp1wpli.fsf at dwp.des.no>, =?iso-8859-1?q?Dag-Erling_Sm=F8rgrav?= writes:
>Poul-Henning Kamp <phk at phk.freebsd.dk> writes:
>> So pending any really good arguments to the contrary I plan to increase
>> HZ to 1000 on i386 this weekend.
>
>two good arguments:
>
>  1) I'm already working on this, and you know it, since I asked you
>     about it in Karlsruhe.

Ahh, sorry, I got the impression that you were not going to do it on
your own.

>  2) 1000 is not a good choice, because we can't approximate it well
>     with the 8254.  1268 is better, 1381 is even better, 1903 is the
>     best we can do between 1000 and 2000, 2299 is the best we can do
>     between 1000 and 5000.

I played with it here and found that 1000 actually works better than 941.
(1193182 / 941 ~= 1268) because the 941 gives a slow beat against 1Hz.

It is actually preferable to have a fast beat (jitter) than a slow
beat (wander), particularly for people doing benchmarks.

Poul-Henning

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.