Re: Should I use Linux to develop driver for specialized ISA card?

["Christopher Friesen" <cfriesen@nortelnetworks.com>]

Fred wrote:
> 
> I'm  curious, Alan, Why? I'm a hardware developer, and I would have assumed
> that linux would have been ideal for real time / embedded projects? (routers
> / controllers / etc.) Is there, for instance, a reason to suspect that linux
> would not be able to respond to interrupts at say 8Khz?
> of course I know nothing of rtlinux so I'll read.

I'm involved in a project where we are using linux in an embedded application. 
We've got a gig of ram, no hard drives, no video, and the only I/O is serial,
ethernet and fiberchannel.

We have a realtime process that tries to run every 50ms.  We're seeing actual
worst-case scheduling latencies upwards of 300-400ms.

So while interrupts can be handled pretty quickly, you'll want to make sure that
your buffers are big enough that your userspace app only needs to run every half
second or so.

You may be better off with rtlinux if you need better response. (Or if you're on
x86 hardware you could look at the low-latency patches.)


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