SMP Folding @ 50% to 75% = 0 Progress?!
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October 13, 2011, 04:38 PM
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Sounds like an affinity problem. That is, thread imbalance such that the core is spending a big chunk of its CPU cycles waiting.
Think of it like this:
00:00 Thread 1 starts job 1a
00:00 Thread 2 starts job 2a
00:30 Thread 1 finishes job 1a
00:45 Thread 2 finishes job 2a
00:45 Thread 1 starts job 1b
00:45 Thread 2 starts job 2b
Since thread 1 can't start job 1b until it gets the job 2a information from thread 2, then its CPU time between 00:30 and 00:45 is just cycling in wait, not really doing anything. The more threads you have, the more they will have to wait if their cycles fall out of symmetry, and when this happens to a symmetrical task with linear progression such as fah, it could cause all kinds of problems.
So to reduce CPU usage, you would probably be better served by doing all of the following:
a) Leaving usage at 100% in the client config
b) Using the smp flag to reduce the number of processing threads available to fahcore
c) Using a program like WinAFC to assign and limit the fahcore to specific threads
That way, the process will maintain better symmetry and waste fewer CPU cycles waiting.
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