Date: Tue, 16 Dec 1997 11:59:18 +0000 (GMT) From: Andrew Gordon <arg@arg1.demon.co.uk> To: John Kelly <jak@cetlink.net> Cc: FreeBSD Hackers <hackers@freebsd.org>, Mike Smith <mike@smith.net.au> Subject: Re: 3com 3c509 card Message-ID: <Pine.BSF.3.91.971216115308.12854C-100000@server.arg.sj.co.uk> In-Reply-To: <34964c48.30733173@mail.cetlink.net>
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On Tue, 16 Dec 1997, John Kelly wrote: > On Mon, 15 Dec 1997 23:51:31 -0800 (PST), Tom <tom@sdf.com> wrote: > > > Also, the ed driver supports shared memory cards like the SMC Ultra 16. > >Fastest ISA ethernet you can get. > > I replaced an NE2000 clone with a SMC Ultra 16, thinking shared memory > would consume far less CPU than PIO with an NE2000. But it seems to > be about the same. Have you got a _real_ (no longer available) Ultra here? Testing with FTP (on a 486), I get about 600-700kbyte/sec with NE2000s, and 900-1000kbyte/s with SMC Ultra. However, the "EtherEZ" which has replaced the Ultra appears to be a bit of a lemon - giving rather inconsistent performance (dropped packets) and even when not dropping packets, worse throughput than the Ultra. This appears to be due to its reduced buffer size (8K vs. 16K); also, I notice that it only has one chip for the 8K RAM (vs. 2 chips on the Ultra) - so, although still notionally a 16-bit card, I suspect it might be multiplexing accesses to a single 8-bit wide device and hence needing to insert wait states. I haven't actually proven this theory, but the performance is certainluy not good. (above tests done with several examples of each type, so I'm not suffering from faulty cards).home | help
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