Messages in this thread | | | Subject | Re: Missed jiffies | From | (Eric W. Biederman) | Date | 16 Feb 2002 11:44:30 -0700 |
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Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
> > My system looses about 8 seconds every 20 minutes. This is reported > > by ntp and verified by comparing 'date' to 'hwclock --show' and a wall > > clock. > > > > My system is a x86 Dell laptop with HZ=1024. > > > > I am quite certain that the issue is the System Management Interrupt > > (SMI). > > Possibly and if it is you can't really do much about it.
Except usually the truly annoyed can reprogram the chipset so an SMI interrupt is not generated. But I doubt that is practical on a laptop.
> ACPI may help here but lots of vendors implement their ACPI subsystem using > I/O cycles to jump into SMM mode so its game over again.
Hmm. I wonder if this is a simple transition technique or if it is their long term strategy.
Now I'm going to research and see if SMM mode is supported on with x86-64 and ia64. With ACPI the case can at least be made that SMM mode is not strictly necessary and should be dropped. I'm dreaming but if the processors didn't have this super protected mode, BIOS vendors and operating system vendors would be force to cooperate on these issues.
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