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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Testing Bandwidth performance
----- Original Message ----- From: "David G. Andersen" <[email protected]> To: "todd glassey" <[email protected]> Cc: "Jared Mauch" <[email protected]>; "Martin Hannigan" <[email protected]>; "Wojtek Zlobicki" <[email protected]>; "Alan Sato" <[email protected]>; <[email protected]> Sent: Wednesday, June 26, 2002 6:30 AM Subject: Re: Testing Bandwidth performance > > On Wed, Jun 26, 2002 at 06:18:00AM -0700, todd glassey mooed: I have never been referred to as bovine before. I usually describe myself as a small polar bear... Hmmm. > > > > Oh and use something like a SNIFFER to generate the traffic. Most of what we > > know of as commercial computer's cannot generate more than 70% to 80% > > capacity on whatever network they are on because of driver overhead and OS > > latency etc etc etc. It was funny, but I remember testing FDDI on a UnixWARE > > based platform and watching the driver suck 79% of the system into the > > floor. > > Btw, if you've got a bit of time on your hands, the Click router > components have some extremely-low-overhead drivers (for specific > ethernet cards under Linux). Good Point. > They can generate traffic at pretty > impressive rates. They used them for testing DOS traffic for a while. > > http://pdos.lcs.mit.edu/click/ Still there are very few parametric engines that will generate more than 100Mb/S traffic - continuously. > > (Most of the driver overhead you see is interrupt latency; Depends on which OS you are running, and what encapsulation or other packaging/unpackaging is done in the Driver also accounts for a substantial amount of the compute model. If those services are done mostly in HW then the systems I have played with will give you up to about 80% capacity. And on ethernet that is not Collision-Free (i.e.run as full duplex), then you have to deal with the line characteristics so with both engines competing to flood the net you may actually get less than 80% total performance... > click > uses an optimized polling style to really cram things through). Also, > the new FreeBSD polling patches should make it so you can get more > throughput from your drivers when doing tests. I understand there are > similar things for Linux. The Linux Router Project has similar features. > > -Dave > > -- > work: [email protected] me: [email protected] > MIT Laboratory for Computer Science http://www.angio.net/
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