Re: Mustek scanner bug

Rogier Wolff (R.E.Wolff@BitWizard.nl)
Sat, 14 Mar 1998 09:05:25 +0100 (MET)

becka@rz.uni-duesseldorf.de wrote:
>
> > I have a Mustek Paragon 1200SP. While it is scanning it locks the entire
> > system (it even blocks the mouse!). When the scan is finished everything
> > starts working again, but a tipycal scan is VERY SLOW. I have followed all
> > the hints given in the documentation and more...
> >
> > I also tried removing all other SCSI devices from the bus and increasing
> > the SCSI buffer in the kernel. It did not improve much...
> > The situation is particularly annoying, since the scanner is placed on our
> > server, and every time someone wants to scan, it hangs all our little
> > cluster!
>
> What SCSI adaptor are you using ? The NCR53c400 that came with mine is
> known to take great pieces of CPU, because it has no interrupt.
>
> I cannot strictly confirm this, but AFAIK with a good SCSI adaptor, all
> should be well.

Well, if there are scsi disks on the SCSI bus that is scanning, things
can get pretty bad. Especially if the scanner doesn't do
disconnect/reconnect.

The scanner holds the bus for a few seconds at a time. And SANE tries
to keep the scanner busy, so it will keep on issueing commands as fast
as possible. The disks only gets a few blocks back and forth in
between. As you Xserver eventually will hit a minor pagefault, it will
need that before it can move your mouse again. That pagefault ends up only
getting resolved after the scan completes.....

Roger. 

-- 
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