Re: System response time for Linux

From: Peter Monta (pmonta@terayon.com)
Date: Wed May 10 2000 - 20:10:06 EST


> I have a realtime application, which is basically a PCI device driver. Since
> the application needs a system response time around 50us

Is 50us a hard deadline? If so, RTLinux is certainly what you want;
if you can tolerate occasional few-millisecond delays, the plain
kernel may suffice.

For RTLinux 50us sounds reasonable, depending on what the software
must do to service an interrupt. If your device is the not the only
thing sitting on the PCI bus, you'll want to be careful about
PCI-arbiter settings like latency timer: with long bursts and several
PCI devices, worst-case latency to grab the bus can get into the tens
of microseconds.

If your hardware is available (or even if it isn't :-) ), I'd suggest
a benchmark. If the hardware can support timers, can see everything
with software; otherwise a storage scope watching stimulus and response
will do nicely.

Cheers,
Peter Monta pmonta@terayon.com
Terayon Communication Systems

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