Author: Robert Hyatt
Date: 20:02:51 09/03/00
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On September 03, 2000 at 20:13:57, Aaron Gordon wrote: >What about with channel bonding in linux? For example you could get 6 100mbit >nic's per pc to have 0.6Gbit (or if you've got some serious cash then 6 1gbit >NICs). As soon as I get some money I'm going to try to experiment with the small >linux cluster I've got here, maybe go with three 100mbit nics per pc. >Anyway, it's a thought.. should help the bandwidth problem a lil'.. No, sorry. Totally wrong idea. The PCI bus _is_ the problem. It can sustain about 100mbytes/second. If you put 6 NICS in the machine, you are talking about roughly 10mbytes/sec per nic and you really can't drive the things at 100mbits/sec... I have been able to get roughly 70 mbits/sec as an upper bound. You could go to something faster (giganet) but then you run into the PCI bus limit, and trying to bond more than one of those will result in bus saturation... at the 100mbytes/second limit... We are talking about the max bandwidth between the CPU and memory, which is the bottleneck in the PC, and that is also where the C90 totally cooks the PC. IE the C90 has 16 cpus at a 2ns clock cycle (500mhz roughly). In one clock cycle, the machine can do 4 64 bit memory reads, and two 64 bit memory write. If you multiply that out, that is 48 bytes per cycle, times 16 cpus, which is 500,000,000 * 48 * 16. Compare that memory bandwidth to the PC bandwidth and you see why the C90 came out at 30 million dollars when they were first delivered. That is roughly 4 x 10^11 bytes per second... 400,000,000,000 bytes per second. Think about that number for a second. 400 gigabytes per second... compared to 100 megabytes per second... :) Then you realize just how far the PCs have to go...
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