Date: Mon, 26 Jun 1995 02:12:57 -0700 (PDT) From: "Rodney W. Grimes" <rgrimes@gndrsh.aac.dev.com> To: rcarter@geli.com (Russell L. Carter) Cc: hackers@freebsd.org Subject: Re: FreeBSD as a router Message-ID: <199506260912.CAA03217@gndrsh.aac.dev.com> In-Reply-To: <199506252111.OAA01741@geli.clusternet> from "Russell L. Carter" at Jun 25, 95 02:11:53 pm
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> > |> R. Grimes writes..... > |> > |> >The SMC 9332 EtherPower 10/100 is a bus master device with no memory > |> >on it at all. It uses host memory for packet buffers and for all > |> >practical purposes this can be as much memory as you want to through > |> >at it! > |> > > |> As long as you can get the bus. You don't want this on a 100mbs media > |> device. The card (or controller) needs some buffering or you'll be in > |> trouble with a heavy burst. > | > |I don't think that a 10MByte a second memory demand is going to have > |much of a problem at all on a 132MB/sec (theroy) or 100MByte/sec (measured) > |bus like PCI. > > Well, that 100 MBytes/sec was mem to mem, right? Not going through the > bus to a device. For that the best I've ever heard of with the current > generation PCI chipsets is 18 MBytes/sec. If anybody knows of > device<->mem faster than 18 MBytes/sec I would appreciate a pointer to it. 18MB/sec is PCI cycles to I/O addresses, it should (and I need to go measure this on a video card) be 100MB/sec for bus mastered DMA access for long bursts. Or for access memory that resides on the PCI bus. (Any one seen a PCI memory card yet??) -- Rod Grimes rgrimes@gndrsh.aac.dev.com Accurate Automation Company Reliable computers for FreeBSD
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