Date: Wed, 25 Jul 2001 14:07:37 -0400 From: Bosko Milekic <bmilekic@technokratis.com> To: Zhihui Zhang <zzhang@cs.binghamton.edu> Cc: Terry Lambert <tlambert2@mindspring.com>, vishwanath pargaonkar <vishubp@yahoo.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: cluster size Message-ID: <20010725140737.A25132@technokratis.com> In-Reply-To: <Pine.SOL.4.21.0107251350010.20991-100000@opal>; from zzhang@cs.binghamton.edu on Wed, Jul 25, 2001 at 01:51:51PM -0400 References: <3B5E69C5.3D3C259E@mindspring.com> <Pine.SOL.4.21.0107251350010.20991-100000@opal>
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On Wed, Jul 25, 2001 at 01:51:51PM -0400, Zhihui Zhang wrote: > > > On Tue, 24 Jul 2001, Terry Lambert wrote: > > > Zhihui Zhang wrote: > > > > Hi, > > > > in freebsd can we change the cluster size from 2048 > > > > bytes.If yes how can we do that? > > > > do we have to configure in some file? > > > > > > You must be asking why the mbuf cluster size is chosen as 2048, right? It > > > is probably a tradeoff between memory efficient and speed. > > > > Ask yourselves: > > > > "What is the minimum cluster size I would have to have > > to be able to contain the maximum MTU worth of data, > > yet remain an even multiple of sizeof(mbuf) -- 256 > > bytes?" > > A dumb question: why even not odd multiple? > > -Zhihui It actually has to do with the fact that 2K is the only size equal to or greater than the maximum MTU worth of data that can be multiplied to a page size without any leftover (in other words, page size modulo 2K is zero). -- Bosko Milekic bmilekic@technokratis.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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