Re: voluntary-preempt T3 latency spikes with fan speed change

Andrew Rodland
2004-10-11T17:07:29Z

torbenh@gmx.de wrote:

>
> hi...
>
> i am seeing latency spikes (ie jack xruns) when the fan of my
> asus l3d laptop changes speed.
>
> is there any chance to fix this ?
> i have turned off acpi in the kernel, as this gives me latency spikes
> all over.
>
> i am quite new to the VP patches, and want to help where i can.
>
> i also got a quite strange latency trace here:
>
> could someone sched some light on this please ?
>

I can't say for certain, but I'm guessing that your laptop has a deeply
broken BIOS that implements ACPI and suchlike by using SMM, which blocks
out interrupts, and there's nothing, I believe, you can do about it.
Disabling ACPI seems sensible; at least you can avoid causing these delays
intentionally, but if some sensor interrupt triggers a flip into SMM to
enable the fan, you're just screwed for a number of milliseconds.

Andrew