Garth,
That's what I was trying to address in my previous email when I
mentioned the latency parameter of a PCI card. In fact, I didn't
think of priorities in the interruption request level when I read
your first question.
Anyway, an ill-behaved PCI card (with a wrong choice of latency
and under a heavily loaded demand) can be really bad for any application
(real time or not). I've read about some "pathological" cases where a
card hold the bus (holding the CPU, other PCI cards, etc) forever by
taking too long to release the bus (larger latency) and getting back
in the end of the queue for another transfer before any other card
can gain access.
As I said, those are "pathological" cases, but if you need to be
100% sure, you might have to deal with them. Unfortunately that's not
my strong side :-) and I don't think I can help much. I just wanted
you to hear about it so you can do some investigation by yourself. ;-)
Guilherme
>Date: Wed, 20 Oct 1999 14:47:28 -0700
>From: "Garth Gaddy" <[EMAIL PROTECTED]>
>Subject: Re: [rtl] RTL or RTAI: Determinism while using SCSI Raid
>
>It sounds like the critical point is how long the SCSI Raid pci card will hold
the processor. Anyone have any idea how long a worst case might be?
>
>Garth Gaddy
>
-------------< G. N. DeSouza >-------------
---------< [EMAIL PROTECTED]>---------
--< http://rvl1.ecn.purdue.edu/~gnelson >--
--- [rtl] ---
To unsubscribe:
echo "unsubscribe rtl" | mail [EMAIL PROTECTED] OR
echo "unsubscribe rtl <Your_email>" | mail [EMAIL PROTECTED]
----
For more information on Real-Time Linux see:
http://www.rtlinux.org/~rtlinux/
