Re: Why HZ on i386 is 100 ?

Chris Friesen
2002-04-16T16:03:57Z

Rik van Riel wrote:
>
> On Tue, 16 Apr 2002, Mark Mielke wrote:
>
> > Increasing the HZ can only improve responsiveness, however, there is a
> > cost (mentioned by others). The cost is that the scheduler is executed
> > more often per second. If the scheduler does the same amount of work
> > per tick, but there are more ticks per second, the scheduler does more
> > work overall, and the CPU is free for use by the processes less.
>
> Why are you discussing Linux 1.2 ?
>
> Linux is not running the scheduler each cpu tick and hasn't
> done this for years.

Very true. However it does run the timer/clock code every tick, which is still
additional overhead when the tick time is reduced.

The basic idea (increased overhead at higher HZ) is sound, the details are not.

Chris

--
Chris Friesen | MailStop: 043/33/F10
Nortel Networks | work: (613) 765-0557
3500 Carling Avenue | fax: (613) 765-2986
Nepean, ON K2H 8E9 Canada | email: cfriesen@nortelnetworks.com