Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt

Denis Vlasenko
2005-07-10T10:45:28Z

On Saturday 09 July 2005 01:08, Linus Torvalds wrote:
>
> On Fri, 8 Jul 2005, Andrew Morton wrote:
> > >
> > > The previous value here i386 is 1000 --- so why is the default 250.
> >
> > Because 1000 is too high.
>
> Yes. I chose 1000 originally partly as a way to make sure that people that
> assumed HZ was 100 would get a swift kick in the pants. That meant making
> a _big_ change, not a small subtle one. For example, people tend to react
> if "uptime" suddenly says the machine has been up for a hundred days (even
> if it's really only been up for ten), but if it is off by just a factor of
> two, it might be overlooked.
>
> So 1kHz was a bit of an overkill, but it worked well enough that we never
> really got around to changing it.

There are lots of HZ/100 in the kernel. With either 100 or 1000 it divides exactly,
but with 250 it's wrong by 20%.
--
vda