Return to BSD News archive
Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.mel.connect.com.au!news.mel.aone.net.au!news-out.internetmci.com!peerfeed.internetmci.com!news.msfc.nasa.gov!news.sgi.com!sdd.hp.com!hp-pcd!hpbs2500.boi.hp.com!hpax!cupnews2.cup.hp.com!raj From: raj@cup.hp.com (Rick Jones) Newsgroups: comp.unix.bsd.freebsd.misc,comp.unix.bsd.misc Subject: Re: 100Base-TX: where's the bottleneck? Followup-To: comp.unix.bsd.freebsd.misc,comp.unix.bsd.misc Date: 16 Nov 1996 02:28:06 GMT Organization: Hewlett-Packard's Network Computing Division Lines: 26 Message-ID: <56j8rm$gtu@hpindda.cup.hp.com> References: <327D4EE8.2D@cplabs.com> <55jkrt$7jc@cynic.portal.ca> <327E37E4.5AD4@cplabs.com> <55t6lf$9km@hpindda.cup.hp.com> <55truo$d87@nntp1.best.com> Reply-To: raj@cup.hp.com NNTP-Posting-Host: hpindio.cup.hp.com X-Newsreader: TIN [version 1.2 PL2.10] Xref: euryale.cc.adfa.oz.au comp.unix.bsd.freebsd.misc:31176 comp.unix.bsd.misc:1540 Matt Dillon (dillon@flea.best.net) wrote: : This sort of thing is where PCI DMA really starts to show its suds : as compared to ISA. You actually *could* drive a gigabit ethernet : (100 MBytes/sec = 1000 MBits/sec) via PCI, though it wouldn't leave : much room for anything else. Still, with a DMA based driver and : a pentium pro > 150 MHz, there would possibly even be enough cpu to : run a TCP stack at that speed :-) Aye, there's the rub - is there enough CPU. : A pentium pro 200 with parity non-edo ram has about 200 MBytes/sec of : dynamic ram throughput. The PCI bus has 133 MBytes/sec of throughput : (and I've actually run PCI DMA at 115 MBytes/sec, so I know it can : do it!). No problem ! :-) :-) :) : The real question is what is the Interrupt/TCP/IP stack overhead for : FreeBSD on a pentium-pro 200? Well, fire-up a netperf test with 10 or 100BaseT, I doubt it really matters so long as they both have decent drivers (DMA, not PIO) and measure the CPU usage. If the machine takes more than 1% CPU to do 10 BaseT or 10% to do 100 BT, it won't do link-rate 1000BT ;) rick jones