Date: Sat, 2 Sep 1995 11:59:34 -0400 From: dennis@et.htp.com (dennis) To: Bruce Evans <bde@zeta.org.au> Cc: hackers@freebsd.org Subject: Re: novell ne2000 cards with FreeBSD...opinions? Message-ID: <199509021559.LAA22490@mail.htp.com>
next in thread | raw e-mail | index | archive | help
>>Yeah, I just looked at the driver and saw the programmed IO cruft in there >>to deal with the novell cards. Bummer. Someone mentioned that some of the >>cards really do have shared memory and can run just like the SMC and 3COM. >>Do you know anything about this? > >Shared memory on my NE2000/WD8013EBT card is 50% faster, but that isn't >saying much. The driver spends half its time bcopying to the shared >memory instead of more that half its time doing explicit i/o instructions. >The speeds are something like: > > i/o instructions: 2MB/sec > bcopy: 3MB/sec > IDE disk controllers: 3.3MB/sec PIO mode 0 (or 1?) spec > 8MHz ISA bus max: 4MB/sec > The bus transfer itself is a pretty small piece of the latency puzzle. But with a PIO card you have setup operations for every transfer...whereas with shared memory you can access individual bytes and the buffer without setup latency. db
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199509021559.LAA22490>