Loosing timer interrupts with ACPI

Loosing timer interrupts with ACPI

[Serguei Miridonov]

When periodically reading /proc/acpi/battery/BAT0/info (once 
per second), running "adjtimex --compare=10000" indicates 
slight slowing down of the system clock. It seems that 
reading battery info may lead to loosing timer interrupts.

System: Compaq Presario 900Z notebook
Kernel: 2.4.21-ac1

First time the system clock drift was noticed when running 
akpi applet for KDE: ntpdate time corrections were too 
large. Then I've found that it happens when simply 

To test this, run

adjtimex --compare=10000

in first xterm, and the following script on another xterm:

#!/bin/sh

for i in `find /proc/acpi/battery -type f`
do
    echo $i
    count=0
    while [ $count -lt 30 ]
    do
        cat $i > /dev/null 2>/dev/null
        sleep 1
        count=$[count+1]
    done
done

Serguei Miridonov.