*BSD News Article 72800


Return to BSD News archive

Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!munnari.OZ.AU!news.ecn.uoknor.edu!news.eng.convex.com!newshost.convex.com!bcm.tmc.edu!pendragon!news.msfc.nasa.gov!newsfeed.internetmci.com!in2.uu.net!bigmac1.mcd.com!uunet!inXS.uu.net!zdc!zdc-e!szdc-e!news
From: "John S. Dyson" <toor@dyson.iquest.net>
Newsgroups: comp.os.linux.networking,comp.unix.bsd.netbsd.misc,comp.unix.freebsd.misc
Subject: Re: TCP latency
Date: Tue, 02 Jul 1996 22:45:09 -0500
Organization: John S. Dyson's home machine
Lines: 31
Message-ID: <31D9ECC5.41C67EA6@dyson.iquest.net>
References: <4paedl$4bm@engnews2.Eng.Sun.COM> <4pf7f9$bsf@white.twinsun.com>
				<4qad7d$a5l@verdi.nethelp.no> <4qaui4$o5k@fido.asd.sgi.com> <4qc60n$d8m@verdi.nethelp.no> <31D2F0C6.167EB0E7@inuxs.att.com> <31D9AF0D.4C3AE08C@lambert.org>
NNTP-Posting-Host: dyson.iquest.net
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Mailer: Mozilla 3.0b5Gold (X11; I; FreeBSD 2.2-CURRENT i386)
Xref: euryale.cc.adfa.oz.au comp.os.linux.networking:43974 comp.unix.bsd.netbsd.misc:3924

Terry Lambert wrote:
> 
> John S. Dyson wrote:
> ] Steinar Haug wrote:
> ]
> ] > Pentium local           250 usec
> ] > AMD Linux local         330 usec
> ] > AMD FreeBSD local       350 usec
> ] > AMD Linux -> Pentium    420 usec
> ] > AMD FreeBSD -> Pentium  520 usec
> ] >
> ] > So the difference is quite noticeable. Wish I had another P133
> ] > here to test with, but unfortunately I don't.
> ]
> ] All this TCP latency discussion is interesting, but how does this
> ] significantly impact performance when streaming data through the
> ] connection?  Isn't TCP a streaming protocol?
> 
> It's relevent for Samba and HTTP, which are request/response
> protocols which tend to not take advantage of the sliding
> windows.  For these protocols, the latency per packet counts
> per packet instead of FTP or similar protocols, where it counts
> only once per packet run.
>
So I guess it is time to look at it.  Isn't this likely an
artifact of the sofware interrupt/ast type scheduling in the
BSD code?

John