From: Jim Peters (jim_at_uazu.net)
Date: 2002-03-14 23:42:57
sleeper75se wrote:
> Allow me to suggest some more tests:
>
> What happens if you let the receiver run X-windows and you start
> dragging windows around, as well as changing virtual screens?
> Anything that is heavy on non-preemptible kernel resources is
> good...er, I mean bad. :-)
Even worse. Dragging is usually smooth (dragging the window with
contents), but when I've got the serial input thing running, it goes
jerky, and after every jerk, the serial input stream reports loss of a
few bytes.
> Increasing the priority of the serial port IRQ on Linux
> http://cae.best.vwh.net/irqtune/
Okay, did that, and it didn't help at all. It could be something with
my chipset -- the video mem is shared with system memory -- one of
those all-in-one chipset kind of jobs. (It's got a nice box, though:
Shuttle SpaceWalker SV24)
However, 'irqtune' does make a huge difference on my textmode laptop
-- receiving serial data is now rock-solid at 115200 baud, even when
also scanning the whole hard drive, and this is with DMA turned off.
It even stays solid with another process taking 75% of CPU calculating
sines. I didn't even have to increase priority.
So, I think the problem could well be solved on the laptop.
> Patching the Linux kernel (v2.4.x) so that its latency is reduced.
> You have three patches to choose from:
> http://www.linuxdj.com/audio/lad/resourceslatency.php3#L4
I'll have a look at that sometime.
Jim
-- Jim Peters (_)/=\~/_(_) jim_at_uazu.net (_) /=\ ~/_ (_) Uazú (_) /=\ ~/_ (_) http:// B'ham, UK (_) ____ /=\ ____ ~/_ ____ (_) uazu.net
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