Re: NE2000 slow interrupts safe?
Richard Gooch (Richard.Gooch@atnf.CSIRO.AU)
Fri, 17 Apr 1998 10:35:11 +1000
Rogier Wolff writes:
> Richard Gooch wrote:
>
> > On my tests I noticed quite a spread of times. When I send short
> > packets, then yes, the times are around a few hundred
> > microseconds. However, for longer packets, I was getting up to 2
> > milliseconds. And my measurements were consistent with the results
> > other were getting with pSOS. I first instrumented almost the whole
> > interrupt handler, then later just instrumented the block transfer
> > routine and got the same results.
>
> Rule-of-thumb calculation: ISA bus cycle costs 1 us (one microsecond).
> 1500 bytes -> 750 transfers (Ne2000 is 16bit card) -> 750 us.
>
> I'd say 2000 us is quite long, 300 us is a pretty fast.
>
> I guess that you can have ne2000's that are slower than others. Maybe
> 300 us was a PCI card?
Nope. All tests were on an ISA bus. The shorter times were due to
shorter packets.
Regards,
Richard....
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