Date: Sat, 24 Jun 1995 12:14:36 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: dennis@et.htp.com (dennis) Cc: freebsd-hackers@freebsd.org Subject: Re: FreeBSD as a router Message-ID: <199506241914.MAA13409@gndrsh.aac.dev.com> In-Reply-To: <199506241710.NAA19368@mail.htp.com> from "dennis" at Jun 24, 95 01:10:00 pm
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> > >> > >> > >> On Thu, 22 Jun 1995, Jordan K. Hubbard wrote: > >> > >> > That said, be aware that any kind of UN*X box doesn't exactly compete > >> > with a Cisco in terms of performance. They throw raw hardware at the > >> > problem whereas we have to do it the hard way, in software. > >> > >> The bottleneck certainly can't be in the CPU can it? Where is the > >> bottleneck with PCI and a good 486 motherboard? > > > >The bottleneck is that you have to wait for full frame reception > >before you get an interrupt to tell you to go look at the header > >to decide what to do with the packet. > > > >In dedicated router hardware they use the trick of interrupting > >the CPU after N bytes have been recieved (N is programmable) so > >they can actually decide what to do with the packet before it is > >even completly received. > > > > > This is not necessary to get good throughput, although it wouldn't hurt. You > can still get 5mbs without this, which is plenty. Not when you start looking at 100MB/sec ethernet it isn't!!! Sure 400 to 500 KByte/sec for 10MB/sec ethernet routing is just fine by me, but as soon as I reproduce the numbers for 100MB/sec routing you will see what I mean about we need to make some improvements. We need to get that routing performance into the 50MB/sec range and we are not even close. (I seem to recall about 20MB/sec, but am not sure right now, too many numbers floating around in my head). -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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