Keyboard problem under heavy load in recent -ac kernels

[Adrian Bunk]

Hi,

I've seen several times the following problem (it's not 100% but
relatively good reproducible) in 2.4.19-pre3-ac kernels (I've seen it in
at least ac4 and ac6) but not in -pre3 or -pre4:

Hardware:
- AMD K6/300
- VIA vt82c586b (rev 41) IDE with two 20 GB drives (using UDMA(33))
- 128 MB RAM

Workload:
- X (fvwm, XFree86 4.1 on a Debian unstable)
- xmms
- heavy disk IO on the same HD, e.g:
  - two "tar xzf linux-2.4.18.tar.gz"
  - one "nice rm -rf linux-2.5.7"

Starting from some point no single letter I type on my keyboard reaches an
xterm when I try to write something there but X is still responsive. This
means I can start applications and work inside them - but at the same time
no single letter arrives when I try to type in an xterm. After this
phenomenon is over all letters I typed in different xterms occur in the
xterm that is active at this time.

To make it more visible:
I tried to start Gimp from the fvwm menu after I typed a letter - and
Gimp has completed its startup before the letter arrived in the xterm.

Is there any information I should collect when I observe this the next
time?

cu
Adrian

BTW: I'll be away from home for one week which means I might not be able
     to reply to emails immediately.