On Thu, Feb 03, 2000 at 10:50:32 -0800, Matthew Jacob wrote:
>
> > The FreeBSD driver (written by Matt Jacob) is based on the Linux driver,
> > which Intel wrote, and he hasn't yet managed to get decent throughput
> > through the cards. (Maybe Matt will comment.) They also only have 64K of
> > memory on board, which is insufficient for a heavily loaded server, IMO.
>
> That's not memory- that's FIFO- there are two of them, I believe, one for
> receive, the other for xmit. You can devote 64k to ring descriptors for
> receive- that's 4096 descriptors- each able to manage a 2k buffer. And
> you can have two receive rings. You can have the same size for xmit.
>
> So, the receive performance bottleneck for this chip/board will be in how good
> your PCI implementation is at first followed by how low an amount of
> interrupt latency for reinstruct. If your PCI implementation can keep up with
> Gigabit speeds, you're fine. If not, I'm not sure that 512K or 1MB buffering
> buys you much.
I think the memory would come in handy on a heavily loaded system, since
you would gain a little extra time in case you were a little late servicing
interrupts. i.e. it would smooth out the bumps a little bit.
If your PCI implementation won't keep up with gigabit speeds, you'll just
go slower. :) Most newer systems (e.g. 440BX) shouldn't have any trouble
doing a reasonable amount of speed over gigabit ethernet, though.
Ken
--
Kenneth Merry
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