From owner-freebsd-current Thu Jul 13 8:34:30 2000 Delivered-To: freebsd-current@freebsd.org Received: from turtle.looksharp.net (cc360882-a.strhg1.mi.home.com [24.2.221.22]) by hub.freebsd.org (Postfix) with ESMTP id 9A06437C4F0; Thu, 13 Jul 2000 08:34:17 -0700 (PDT) (envelope-from bandix@looksharp.net) Received: from localhost (bandix@localhost) by turtle.looksharp.net (8.9.3/8.9.3) with ESMTP id LAA27077; Thu, 13 Jul 2000 11:34:14 -0400 (EDT) (envelope-from bandix@looksharp.net) Date: Thu, 13 Jul 2000 11:34:14 -0400 (EDT) From: "Brandon D. Valentine" To: Stephen McKay Cc: Stefan Esser , Bill Paul , freebsd-current@FreeBSD.ORG Subject: Re: dc driver and underruns (was: Strangeness with 4.0-S) In-Reply-To: <200007131246.WAA05918@dungeon.home> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, 13 Jul 2000, Stephen McKay wrote: >>Guess it will show up if you measure latencies (or your application is >>doing lots of RPCs). But as soon as there is a cheap 100baseT switch in >>the path to the destination, there will be store-and-forward at work ;-) > >Does anyone here actually measure these latencies? I know for a fact >that nothing I've ever done would or could be affected by extra latencies >that are as small as the ones we are discussing. Does anybody at all >depend on the start-transmitting-before-DMA-completed feature we are >discussing? I don't like the idea of removing that feature. Perhaps it should be a sysctl or ifconfig option, but it should definitely remain available. Those minute latencies are critical to those of us who use MPI for complex parallel calculations. Brandon D. Valentine -- bandix at looksharp.net | bandix at structbio.vanderbilt.edu "Truth suffers from too much analysis." -- Ancient Fremen Saying To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message