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On Fri, 15 Sep 2000, jamal wrote:

> Only the timer runs at HZ granularity ;-<

Some cards provide their own high resolution timers; latest 3Com cards
provide several with different purposes (none currently used). The
question is how many of these also provide the Rx early interrupts.
You also mentioned an auto-tunable Rx mitigation scheme. How do you
implement it without using hardware timers ?

> 20Msec is probably too much time. If my math is not wrong, 1 bit time in
> a 100Mps is 1 ns; 64 bytes is 512ns.

I think your are wrong by a factor of 10 here, 1 bit time at 100Mbps
should be 10 ns. Then 64 bytes is 5.12 us (u=micro). Anyway, this is
comparable with the time needed to reach ISR, so you can have several
(but small number) of packets already waiting for processing.

> You use the period(5-10micros), while waiting
> for full packet arrival, to make the route decision (lookup etc).
> i.e this will allow for a better FF; it will not offload things.

Just that you span several layers by doing this, it's not driver specific
anymore.

Sincerely,

Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu@IWR.Uni-Heidelberg.De


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