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

Theodore Ts'o
2005-07-11T14:10:05Z

On Mon, Jul 11, 2005 at 02:23:08PM +0100, Alan Cox wrote:
> > > Because some machines exhibit appreciable latency in entering low power
> > > state via ACPI, and 1000Hz reduces their battery life. By about half,
> > > iirc.
> > >
> > Then the owners of such machines can use HZ=250 and leave the default
> > alone. Why should everyone have to bear the cost?
>
> They need 100 really it seems, 250-500 have no real effect and on the
> Dell I tried 250 didn't stop the wild clock slew from the APM bios
> either. I played with this a fair bit on a couple of laptops. I've not
> seen anything > 20% saving however so I've no idea who/why someone saw
> 50%

The real answer here is for the tickless patches to cleaned up to the
point where they can be merged, and then we won't waste battery power
entering the timer interrupt in the first place. :-)

- Ted