Date: Mon, 3 Apr 1995 09:18:02 +0200 (MET DST) From: Luigi Rizzo <luigi@labinfo.iet.unipi.it> To: davidg@Root.COM Cc: hackers@FreeBSD.org Subject: Re: NE2000 Plus performance Message-ID: <199504030718.JAA09037@labinfo.iet.unipi.it> In-Reply-To: <199504020459.UAA00129@corbin.Root.COM> from "David Greenman" at Apr 1, 95 08:59:00 pm
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> It's not supported. I didn't even know of the NE2000+ existence until you > mentioned here. Ok. A couple of questions about network ards and drivers, though: 1) how much faster are memory-mapped cards wrt io-mapped ones ? Is it just the clock cycle per word that you save in transferring data with MOVSW instead of INSW, or there is more (e.g. the driver does more or less random access to the board, thus has to waste time specifying the address of the desired data quite often) ? 2) not long ago,, if memory serves, it was mentioned that the network drivers in freebsd use only one buffer for tx data, and the rest of the memory for rx packets. If this is true, how can it work at full network speed ? I mean, while the buffer is busy because the packet is being sent, you cannot refill it to send the next packet back-to-back. Unless, of course, the "one tx buffer" was actually "one tx buffer for data queued to the controller", and there is other memory that the CPU can use to prepare the next packet. Thanks Luigi ==================================================================== Luigi Rizzo Dip. di Ingegneria dell'Informazione email: luigi@iet.unipi.it Universita' di Pisa tel: +39-50-568533 via Diotisalvi 2, 56126 PISA (Italy) fax: +39-50-568522 ====================================================================
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