dual processor?
Posted:
17 Jan 2006, 17:31by Daniel Shawul
Is the following a dual processor? I see two graphs per cpu in task manager. Cpu usage is 100% with SMP crafty and 50% for non smp crafty.But the thing that worries me is that the speed up for crafty at the start position is 1.09.
And 1.22 for zappa
< 1 for scorpio
Is this what i should expect?
thanks in advance.
daniel
Re: dual processor?
Posted:
17 Jan 2006, 17:57by Daniel Shawul
crafty slows down by 6x with three threads.
more data tommorrow..
Re: dual processor?
Posted:
17 Jan 2006, 21:25by Dann Corbit
You will see 2 graphs if hyperthreading is turned on.
Basically, hyprethreading is pure B.S. and has no use in chess programming (maybe 1% gain or some pittance).
Otherwise, 2 threads should show 70% gain or so over 1 thread or something is badly broken if you have a 2 CPU machine.
Crafty requires an SMP compile to use more than 1 thread.
Crafty dies in a horrible way if you tell it to use more theads than available CPUs (e.g. on a 2 CPU machine, if you tell crafty to use 4 threads it will lose a huge amount of performance. So it is not like your system that loses slowly.)