Author: Robert Hyatt
Date: 18:50:00 08/11/02
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On August 11, 2002 at 17:34:36, Chris Carson wrote: >On August 11, 2002 at 17:17:09, Jason Jarrells wrote: > >> Bunch of idiots here.. Someone asks a simple question, and you give BS >>statements.. Get a life people. Does anyone know what hardware they are using? >> If not then don't comment on this question... Geez.. > >I do not know and I have also asked this question, perhaps the questions should >be, what is the fastest multi-proc 4 way and 8 way boxes (Intel and AMD). Some data from testing myself... 4-way boxes are very good. With 4-way interleaving, my quad loses about 7% when I test it. IE I run a single instance of crafty, using 1 cpu, and get a precise time to complete a search. I then run _two_ instances of Crafty and measure the same time again. It will be about 7% slower than it was when it ran by itself. If I run three instances of Crafty, one will run about 14% slower. And four makes this 21%. This is a memory and bus issue. The 8-way boxes still use 4-way interleaving. Which means twice as many CPUS, twice as many memory accesses, but the same memory/bus speed as the 4-way box. That is _not_ a recipe for blazing speed. A typical dual processor will slow down about 30% when the second instance of Crafty is run, for example, as most duals do not use any interleaving at all, and the cpus end up competing for memory and starving as a result. It is certainly doable to build an 8-way box with 8-way or 16-way (even better) interleaving. But it drives the cost _up_... With the memory issues, Intel has lagged in the quad and 8-way development, and it might be that the fastest dual is a better machine overall when you figure in the memory loss and the SMP search overhead loss. For example: dual 2ghz would, for Crafty, behave like dual 1.4 ghz processors due to the 30% memory loss, and then with my normal parallel search efficiency of 1.7, it would look like a 2.4ghz processor. quad 700, looks like a quad 553 mhz machine with the 7% per cpu memory loss. Factor in the 3.1x SMP search efficiency and it looks like a single 1.7ghz processor. Which would you take? That kind of math needs to be done for _any_ machine before blindly diving in and using it in a match this important. No doubt it will be done...
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