Date: Mon, 30 Mar 1998 12:40:14 -0600 From: Chris Csanady <ccsanady@friley585.res.iastate.edu> To: "Ron G. Minnich" <rminnich@Sarnoff.COM> Cc: freebsd-hackers@FreeBSD.ORG Subject: Re: Virtual Interface Architecture Message-ID: <199803301840.MAA03732@friley585.res.iastate.edu> In-Reply-To: Your message of "Mon, 30 Mar 1998 12:47:24 EST." <Pine.SUN.3.91.980330123713.4075D-100000@terra>
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>well, there is a via emulation written for linux by bozeman at LBL. You >might see if he would let us have a look. app-app latency is 20 >microseconds or so: good but not earth-shattering, UNET is already about >there anyways. The via spec defines an API that if you conform to you can >pretty much put anything underneath. Do you have any more information on the work that Bozeman is doing at LBL? I would be interested in what his linux implementation looks like, and what kind of hardware he is using it on. I have looked at U-NET. Although it seems like a nice architecture, there doesn't appear to be much ongoing work. The tulip driver has not been updated in a long time, so it will not even useable on most newer tulip based cards. >For real low latency you need a hardware via interface. myrinet will be >releasing one of these this summer. For whatever network you use, there That should be good. :) I was under the impression that you could just write a custom MCP to provide for VIA though, and get the same results. >have to be tags in the packets that allow hardware demux directly to an >application or at least a memory area. As it happens, HIPPI is not that >great this way: you have to put host memory addresses to tell the >destination interface where to put the data. [IMHO, virtual memory >addresses in packets are a really bad way to support hardware demux]. Perhaps not. I really don't have any low level knowlege of hippi, I was just speculating.. >Believe it or not, one thing that is good is ATM, which we've shown in >practice here by building a via-like interface for ATM (it's not >via-compatible because we designed it about three years before intel, >microsoft et. al. thought of via). If you think about it the ATM VCs can >in fact define an application as an endpoint, not a host, unlike Ethernet. >Of course, since the most common use of atm interfaces is to emulate >ethernet (i.e. LANE), this application-endpoint use is not common :=) > >Unfortunately the ongoing ATM disaster (quick: what's the difference >between the Titanic and ATM? your favorite punchline here. [[[ forget it. >it's too easy to make the titanic look good compared to ATM]]]) will >probably mean nobody ever builds via's based on ATM. But Myrinet will >build good expensive VIAs; and there are other good expensive cards >coming. It sure would be nice if we got to some good cheap cards at some >point too: say, a VIA for 100bt that costs about 100 bucks. Yes, it really would be. So far, it looks like Gigabit ethernet is the only cheap/fast networking solution in the near future. Although, without a larger MTU, supporting VIA looks hopeless even on "good" hardware. :( Chris To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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