Date: Fri, 13 Jul 2001 13:29:03 -0400 From: Leo Bicknell <bicknell@ufp.org> To: Matt Dillon <dillon@earth.backplane.com> Cc: Leo Bicknell <bicknell@ufp.org>, Drew Eckhardt <drew@PoohSticks.ORG>, hackers@FreeBSD.ORG Subject: Re: Network performance tuning. Message-ID: <20010713132903.A21847@ussenterprise.ufp.org> In-Reply-To: <200107131708.f6DH8ve65071@earth.backplane.com>; from dillon@earth.backplane.com on Fri, Jul 13, 2001 at 10:08:57AM -0700 References: <200107130128.f6D1SFE59148@earth.backplane.com> <200107130217.f6D2HET67695@revolt.poohsticks.org> <20010712223042.A77503@ussenterprise.ufp.org> <200107131708.f6DH8ve65071@earth.backplane.com>
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On Fri, Jul 13, 2001 at 10:08:57AM -0700, Matt Dillon wrote: > The basic problem with calculating the bandwidth delay product is that > it is an inherently unstable calculation. It has to be a continuous, I think you're doing good work, but I'm concerned you're going down a road that's going to take a very long time to get right. It is not necessary to calculate the bandwidth*delay in order to prevent over- buffering. Preventing overbuffering only requires tracking the maximum bandwidth*delay value, assuming that we always want the ability to buffer that much data. I think the number of cases where it decreases significantly over the peak for a long enough time to make a difference is minimal. Fully knowing the value over time could lead to optimizations like shrinking the buffers, or attempting to prevent some packet loss by not over-increasing the window. However oscellation and other issues I think are going to make this very complex. -- Leo Bicknell - bicknell@ufp.org Systems Engineer - Internetworking Engineer - CCIE 3440 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
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