Date: Tue, 11 Jul 1995 10:17:46 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: dennis@et.htp.com (dennis) Cc: tom@sdf.com, freebsd-hackers@freebsd.org Subject: Re: Wanted: 100bT EISA ethernet recommendation Message-ID: <199507111717.KAA16231@gndrsh.aac.dev.com> In-Reply-To: <199507111518.LAA07160@mail.htp.com> from "dennis" at Jul 11, 95 11:18:12 am
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> > Tom's opinion.... > > > >On Tue, 11 Jul 1995, dennis wrote: > > > >> The question is, who would build one? EISA cards are too expensive to build > >> and EISA is too slow for a 100mbs medium. If someone is making them then > >> I'll bet they have a much bigger marketing dept than engineering. > > > > That's wrong. EISA is fast enough for 100mbs ethernet. > > It can't be wrong, because any way you slice it its an opinion. Under light > load anything will work, but under heavy load its nice if your bus > throughput is greater than the bandwidth. If your EISA card is bus mastering > it can take over your machine under heavy load. For a workstation, sure, but > not for a server. And EISA is too expensive for a workstation. Okay, if you want to slice it up that way, we better throw out all our PCI machines too. Since a P54C CPU has a bus bandwidth capacity of 528MByte/sec and PCI can only do 132MB/sec on 32 bit PCI and 264MB/sec on the non-existent 64 bit PCI. Some one had better sit down and do some serious memory system design as the best memory I have seen in a PC based system falls considerable short of all of this at 75MB/sec. We need a 500+MB/sec I/O channel, and a 1GByte/sec memory channel to keep everything happy, and that is with _todays_ P54C-100, anyone care to recon what we will need next year with SMP P6's being every ones new hot projects?? PCI and EISA buses are _not_ the limiting channel in server applications, nor have they been for the 5 years, it has been memory channel bandwidth problems, plain and simple. If you want to see a real server design look at an Auspex, it can almost meet some of the above numbers. -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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