Re: MP on P5 vs P6

[David Jeske <jeske@home.chat.net> writes:]

>What's your feeling and experience on P5 SMP vs P6 SMP? It's very
>inexpensive to get the required equipment to build a P5 SMP system ($190
>for a Tyan Tomcat 4 dual P5 board, $150 for a P5/166MMX CPU). While a P6
>is somewhat more costly ($290 for a SuperMicro dual P6 board, $275 for a
>P6/180), I would expect it's "SMP" related performance to be significantly
>higher, due both to the better processor bus protocol, and to the dual,
>and private L2 caches.

Yes, you've hit the nail on the head. Also there's the question of
interrupt distribution, which was often assymetric in those low-end P5
"SMP" systems.

>Of course these are all the bargan basement boards and CPUs, and I would
>guess there would be significant gains to using 512k L2 instead of 256k L2
>P6 chips.

Yes, but a coherent L2 cache at 256k is still usable.

>Anyhow, my question goes something like, is the P6 SMP performance
>enough to make it not reasonable to make a dual P5? Knowing that my goal
>here is to put togeather a fairly inexpensive SMP system with the intent
>of experimenting with SMP and responsiveness vs speed tradeoffs that SMP
>provides. (i.e. not necessarily to make the fastest machine I can for the
>dollar)

My recommendation would be to go PPro for sure. If you want to economize,
getting the 256k cache configuration is a better compromise than going to
P5's. Shared L2 cache with write-through L1 is going to make it hard to
scale to any extent at all.

                                                $0.02,
                                                Andy
Received on Wed Sep 10 05:33:37 1997