Subject: Re: [linux-audio-dev] caps lock effect on latency
From: Steve Harris (S.W.Harris_AT_ecs.soton.ac.uk)
Date: Fri Mar 22 2002 - 13:57:38 EET
On Thu, Mar 21, 2002 at 10:50:36 -0500, Taybin Rutkin wrote:
> On Thu, 21 Mar 2002, Paul Davis wrote:
>
> > i noticed from luca's initial report on firm timers that switching the
> > caps lock LED on and off is a notable source of latency in the
> > kernel, on the order of 7msec.
>
> Seems odd. I would have expected the LED to be handled in the keyboard's
> hardware. Maybe only certain models? But I guess it must be universal
> since there is software to toggle the LEDs.
Certainly on AT (and I think PS2) keybaords the LED is controlled by the
CPU. It was a standard way to find out if the kernel had died.
- Steve
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