Hello,
In case this interests anyone...
I've made measurements of PCI interrupt response latencies
around 20 us with a standard deviation around 5 us on a
450 MHz dual PII PC with an ASUS motherboard. We'll soon
test a high-end dual PIII SBC.
Raymond Knopp
[EMAIL PROTECTED] wrote:
>
> On Sun, Jul 02, 2000 at 04:30:19PM +0200, Andrew Tuckey wrote:
> > Hi RTLinux list,
> >
> > I'm new to real-time Linux, so this question may seem a little simple.
> >
> > I'm implementing a machine controller on a dedicated system and I'd like to
> > see if I could do it on a more general system with RTLinux. The system has a
> > sample rate of 10kHz and is currently implemented on a couple of TMS320C40s.
> >
> > I have read a fair amount of the literature on RTLinux available on the web
> > site and it seems to me that the major problem with using RTLinux would be its
> > interrupt latency. From the literature it seems that the worst case interrupt
> > latency can be as high as 15 to 20 us - this is a large amount of the
> > available 100 us and would be a major problem.
> >
> > I would imagine that this interrupt latency is solely caused by the amount of
> > time required to switch contexts - i.e. push all the registers etc.
>
> Good guess, but that's not right. The major factor is purely motherboard
> hardware. We have not measured recently on a good non-ISA SBC, but my
> prediction is that it would be quite fast.
> In fact, we really will measure on a embedded PPC750 and MIPS 7000
> soon and perhaps other people can also run some numbers.
>
> (we have measured 12us for a single ISA bus access !)
>
> --
> ---------------------------------------------------------
> Victor Yodaiken
> FSMLabs: www.fsmlabs.com www.rtlinux.com
> FSMLabs is a servicemark and a service of
> VJY Associates L.L.C, New Mexico.
>
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--
-------------------------------------------
Dr. Raymond Knopp
Mobile Communications Laboratory
EPFL, IN-R Ecublens
CH-1015 Lausanne
SWITZERLAND
Tel: (+41) 21 693 5657
Fax: (+41) 21 693 4312
Email: [EMAIL PROTECTED]
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