Cpu Properties

mack · 2009-09-06, 16:25

what CPU properties (multicore, gHz, cache, etc) provide the quickest results?

CRGreathouse · 2009-09-06, 16:39

More, more, and more/same. Output is directly proportional (ceteris paribus) to GHz and #cores, assuming you run one test per core. More cache doesn't hurt, but I don't think it really helps much in this case.

cheesehead · 2009-09-07, 05:48

There's also the speed with which data can be transferred from memory to the registers for performing arithmetic. This memory bus speed is not always proportional to CPU clock speed, and it is often the most-limiting factor for prime95 computation speed.

Sometimes the program "stalls" for a few CPU cycles at a time because the data needed for the next arithmetic step has not yet arrived from memory (even the L1 cache!) when the CPU is ready to start doing the arithmetic. There was a lot of programming effort devoted to minimizing these "stall" times. Not all could be eliminated.

2009-09-06, 16:25	#1
mack Sep 2009 5 Posts	Cpu Properties what CPU properties (multicore, gHz, cache, etc) provide the quickest results?

2009-09-07, 05:48	#3
cheesehead "Richard B. Woods" Aug 2002 Wisconsin USA 2²×3×641 Posts	There's also the speed with which data can be transferred from memory to the registers for performing arithmetic. This memory bus speed is not always proportional to CPU clock speed, and it is often the most-limiting factor for prime95 computation speed. Sometimes the program "stalls" for a few CPU cycles at a time because the data needed for the next arithmetic step has not yet arrived from memory (even the L1 cache!) when the CPU is ready to start doing the arithmetic. There was a lot of programming effort devoted to minimizing these "stall" times. Not all could be eliminated. Last fiddled with by cheesehead on 2009-09-07 at 05:49

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Some Properties of Mersenne Number Factors	princeps	Miscellaneous Math	18	2011-11-30 00:16
Asymptotic properties of Aliquot sequences	Lothar	Homework Help	1	2011-03-29 09:23
Properties of Mersenne numbers	kurtulmehtap	Math	31	2011-01-10 00:15
Prime95 - Computer Properties wrong memory size	Ravefiend	PrimeNet	4	2008-12-04 23:57
Command prompt properties	henryzz	Lounge	4	2008-11-30 20:46

2009-09-06, 16:39	#2
CRGreathouse Aug 2006 3×1,993 Posts	More, more, and more/same. Output is directly proportional (ceteris paribus) to GHz and #cores, assuming you run one test per core. More cache doesn't hurt, but I don't think it really helps much in this case.