[Click] RX Overruns with eepro100

[Barry Gowan]

> It's not entirely surprising; you may be running
> into the limits of your
> machine here. You didn't say what your PCI bus speed
> and width are, but
> there is certainly going to be a fair amount of
> contention. You're
> essentially trying to forward 20000 1500b packets a
> second -- 240
> Mb/s. This is above a 32/33 PCI bus's maximum
> throughput, and close to the
> max throughput of a 64/33 bus, and that's not even
> counting contention.

Hi Eddie, 
I was on vacation and just got your response.

How do you calculate the PCI max throughput?
I would have thought that 32 bit * 33Mhz would be
1056 Mbps availble throughput on the PCI bus. 
Even if I'm trying to send _and_ receive 240Mbps,
and worst case it takes 2 PCI cycles to transfer 
32 bits, I should still have enough. 
Also, I actually have a 66Mhz PCI bus, and I can 
get even better rates than these by substituting GigE
cards. 
Based on all of this I had basically ruled out the PCI
or the CPU being a bottleneck in this situation. 
Am I missing something?

The reason why I am persuing this is because I have
notes recording that I was able to achieve 8000
1500byte packets per second on an older setup. The
only difference was the version of Click and a
different batch of eepro100 cards. I've replaced the
old version of Click but can't reproduce the rates. 

thanks again, 
BG


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