Path: utzoo!mnetor!uunet!husc6!rutgers!bellcore!faline!ulysses!ggs From: ggs@ulysses.homer.nj.att.com (Griff Smith) Newsgroups: comp.unix.wizards Subject: Re: rdump, Ethernet slowness Message-ID: <3265@ulysses.homer.nj.att.com> Date: 10 Dec 87 16:25:19 GMT References: <788@hsi.UUCP> <1268@laidbak.UUCP> <411@anuck.UUCP> Organization: AT&T Bell Laboratories, Murray Hill Lines: 38 Summary: mostly software delays In article <411@anuck.UUCP>, jrl@anuck.UUCP writes: > > The network transfer rate is good, but the latency is poor. > > How good is this? I know that the network bandwidth is 10Mb, > but when I transfer a 1 MB file, instead of the 10 seconds that > the true bandwidth suggests I might get on an unloaded net, > I find that it takes a minute or more. 10 Mbit/sec == 1.2 Mbyte/sec. True, I never see speeds anywhere near that. I do see 110 Kbyte/sec when I use a CCI POWER 6/32 running 4.3BSD to dump to a DEC VAX 8650, also running 4.3BSD. I think this comes to 9 seconds/Mbyte. I just tried a file copy between those two processor and got 10 seconds/Mbyte, which is just what you wanted. > Is this software delay, Probably; protocol delay, and sometimes processor overload. TCP/IP can chew up a lot of a processor. Our CCI machine has speeded up by a factor of 6 since we first started using 4.3BSD on our VAXen. The first factor of 2 was a windowing strategy mismatch between 4.3BSD and the version of 4.2BSD that was running on the CCI processor. A further factor of 3 resulted when we upgraded to a 4.3BSD+ beta distribution from Berkeley. > maybe someone will make [a controller] that can really feed the > net, which would change my mind about being somewhat put off of > ethernet because it fails to deliver on the single-user throughput. > > John R. Lupien > ihnp4!mvuxa!anuxh!jrl You don't say what flavor of UNIX you are using. Protocol implementations can have a lot of effect on the speed. -- Griff Smith AT&T (Bell Laboratories), Murray Hill Phone: 1-201-582-7736 UUCP: {allegra|ihnp4}!ulysses!ggs Internet: ggs@ulysses.uucp