Multiple CPUS versus one fast CPU
TNWestTex
mcforum at bellsouth.net
Fri Feb 8 15:38:04 UTC 2008
Leslie Satenstein wrote:
>
> There is a Queuing theory conclusion that one cpu at speed 2x is better
> than two cpus at speed x.
>
> The reason is that it takes overhead to schedule two and also each cpu can
> interfere with the other through locks, or memory access.
>
> But to reduce power consumption today, the trend is to 2 cpus at speed x.
> Increasing the speed causes a disproportionate increase in power
> consumption. The two cpu solution generally uses less power.
>
> What is the difference expected in performance? Frankly, it is hard to
> tell, In most cases, it will be ZERO and in other cases (with a lock
> wanted by cpu a which is held by cpu b ) it could be 1% to 2%.
>
> Over an hour, that 1% to 2% would wash out, meaning, you should FORGET
> ABOUT IT.
>
> Go for 2 cpu, shared cache on the die. (Intel or AMD)
>
Some parts of a process are inherently sequential. Those go at the single
processor speed. Amdahl has a limit theorem for parallel processing.
Robert McBroom
--
View this message in context: http://www.nabble.com/Multiple-CPUS-versus-one-fast-CPU-tp15346010p15357591.html
Sent from the Fedora List mailing list archive at Nabble.com.
More information about the fedora-list
mailing list