[ACPI] Re: Re: [PATCH] Don't disable interrupts during EC access

[Stefan S. <se...@gm...>]

On Wed, Nov 17, 2004 at 06:56:07PM +0800, Yu, Luming wrote:

> >may this also help the awfully slow battery polling on some machines
> >(e.g. Dell D600) or is this a completely different case?
> 
> I'm not sure before you clearly describe your specific problem.

Ok, i thought this was a well known problem. (everybody i know seems to have
experience with it :-)

On a Dell Latitude D600 (other machines also, but this i have tested more
extensively), a "cat /proc/acpi/battery/BAT0/info" takes 180msec with
CPU at 600MHz. With CPU at 1700MHz it takes 70msec.

e239:~ # time cat /proc/acpi/battery/BAT0/info > /dev/null

real    0m0.182s
user    0m0.002s
sys     0m0.178s
e239:~ # powersave -f
Speed set to maximum
e239:~ # time cat /proc/acpi/battery/BAT0/info > /dev/null

real    0m0.068s
user    0m0.000s
sys     0m0.067s

this time is 100% kernel time and polling battery makes e.g. DVD playback
"stutter" visibly. The machine basically comes to a halt for ~0.2sec.
-- 
Stefan Seyfried