[linux-audio-user] Laptops for audio

Ryan Gallagher ruinaudio at comcast.net
Wed Feb 9 21:11:53 EST 2005

On Wed, 2005-02-02 at 11:30 -0500, Lee Revell wrote:
> The ACPI/SMM Latency Problem
> While testing the RT preemption patches we discovered that many, many
> laptops are unsuitable for low latency audio work.

> The laptops in question have a BIOS that implements ACPI via SMM.

> According to AC this is a known broken design (in addition to audio, it
> causes these systems to lose timer ticks with HZ=1000), but by his
> estimate more than half of laptops have the problem.
> There is no 100% reliable way to tell if you have the ACPI/SMM problem.

> If you need really low latency, in the mllisecond range, this is a
> showstopper!  So I think the best approach is for the Linux audio
> community to create a "whitelist" of known good laptops.

Wow, I'd heard about this SMM issue but didn't know it was so bad.  I
guess I'm lucky, I've been able to get ~6ms latency with USB.  Dell
Inspiron 5100.

Completely coincidentally, this morning I was just thinking about the
low latency wiki, and wondering if a whitelist would be a good addition.
I also have some webspace to donate to such a cause.


Ryan Gallagher <ruinaudio at comcast.net>

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