lkml.org 
[lkml]   [2004]   [Oct]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: voluntary-preempt T3 latency spikes with fan speed change
From
Date
On Mon, 2004-10-11 at 13:03, Andrew Rodland wrote:
> 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.
>

Many, many people are seeing this problem (weird, often periodic latency
spikes on laptops that go away when ACPI is disabled). This would
explain a lot of weird bug reports. So are most laptops just
incompatible with low latency applications, or are we talking about a
small minority of broken hardware?

Is there any way to tell a priori whether a machine will have this
problem?

Lee

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 14:06    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site