RE: sound breaks up - scheduler prob?

From: Jon Evans (
Date: Sun Jun 18 2000 - 05:10:39 EST


> >> [Me]
> >> So, X 4.0 seems to be the problem. Any ideas as to how to fix it? How
> >> does it manage to grab enough CPU time to cause other tasks to stall,
> even
> >> tasks that have been reniced to -20?

> > [Alan Cox]
> >
> >My guess is XFree 4.0 is hitting the hardware in a way that is locking out
> >the PCI DMA. Can you raise it with the XFree folks see what ideas they have

On Tue, 13 Jun 2000, Bruce Cowan wrote:

> Quite a few VGA cards will force the PCI bus into "PCI retry" state when
> the internal request queue in the VGA chip gets full and the PCI bus is
> trying
> to write another command to the queue. This is very very bad because in that
> state the PCI bus is completely locked out from any device other than the
> one
> forcing the retry. Locking out the PCI bus also locks out the ISA bus since
> it

This was a big clue, thanks Bruce. I had 'option "PCI retry"' for both
cards in my XF86Config. I took those out and it's a lot better than it
was, but still fairly easy to make the sound break up (windowshade a large
window). However when the sound does break up it's not so severe as it
used to be.

Andrew Sharp: yes, I have IRQs unmasked, the commands in my rc.local are:
/sbin/hdparm -u1 /dev/hdc #CD-ROM
/sbin/hdparm -u1 /dev/hdd #CD-ROM
/sbin/hdparm -u1 -d1 -c1 -X66 /dev/hde #HD



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