pdflush uses all cpu-time with 2.6.7 and slow media

[Georg Chini <georg.chini@triaton-webhosting.com>]

Hello,

there seems to be a problem with pdflush and
slow media in 2.6.7. I'm using the packet-writing patch
maintained by Peter Osterlund to write to dvd+rw.
When I copy large files to the dvd, pdflush
starts using all cpu-time up to a point where
the system hangs completely. I found a posting here
with a similar problem concerning nfs and pdflush
(28.04.2004, Brent Cook). This thread mentions,
that the problem is not observable in 2.6.5.
So I tried 2.6.5 and everything works fine if
I set dirty_ratio in /proc/sys/vm to 15. With
the default value of 40 there are still some problems,
but it is way better than 2.6.7-bk12. BTW my machine
is a dual PIII.
Any idea what might cause the problem? Any more
information I should give?
As I'm not on the list, please CC to me in your replies.

Thanks in advance
                  Georg Chini