From owner-freebsd-hackers Thu Nov 29 19:39: 8 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from speedracer.speedtoys.com (mail.speedtoys.com [66.80.10.170]) by hub.freebsd.org (Postfix) with ESMTP id B176E37B416 for ; Thu, 29 Nov 2001 19:38:58 -0800 (PST) Received: from localhost (gemohler@localhost) by speedracer.speedtoys.com (8.11.3/8.11.1) with ESMTP id fAU3uXo79405; Thu, 29 Nov 2001 19:56:33 -0800 (PST) Date: Thu, 29 Nov 2001 19:56:33 -0800 (PST) From: Geoff Mohler X-Sender: gemohler@speedracer.speedtoys.com To: Leo Bicknell Cc: Pierre Beyssac , Josh Paetzel , jc@irbs.com, freebsd-hackers@FreeBSD.ORG Subject: Re: FreeBSD performing worse than Linux? In-Reply-To: <20011129222809.A67159@ussenterprise.ufp.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Dont forget the latencies introduced by routing hardware..Id not expect the average DSL modem to be to snappy about its internal packet forwarding performance. http://rescomp.stanford.edu/~cheshire/rants/Latency.html Thats a good read On Thu, 29 Nov 2001, Leo Bicknell wrote: > On Fri, Nov 30, 2001 at 03:23:45AM +0100, Pierre Beyssac wrote: > > I can't reproduce this result, 16K fills a T1 for 11 ms, which is > > 22000 km (at 2/3 of light speed), enough to get halfway round the > > earth... > > Your math is a little funny. > > 4000 km New York to LA > > c = 300,000 km/sec > > Speed of light in fiber, approximately .66 c, or 198,000 km/sec. > Approximate sum of buffering + serialization delay in the network, > is a 15% penalty, or 168,300 kph. total speed. > > 4000 km one way == 8000 km two way, 8000 / 168300 = 47ms in my book, > theoretial optimum. > > With an RTT of 47ms, you can move 16k per RTT, or or about 340k/sec. > > * If you find a cross country RTT of 47 ms I'll personally send you > $20. around 60-65 is normal for "good circuits", and 70-90 is > not wholely unusual. > > * The 340k/sec assumes perfect network conditions, that is no dropped > or delayed packets. > > Please search the archives. There are reams of information about > this. > > -- > Leo Bicknell - bicknell@ufp.org - CCIE 3440 > PGP keys at http://www.ufp.org/~bicknell/ > Read TMBG List - tmbg-list-request@tmbg.org, www.tmbg.org > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message > --- Geoff Mohler To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message