Author: Robert Hyatt
Date: 15:38:51 08/05/03
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On August 05, 2003 at 17:30:51, Matthew Hull wrote: >Does Crafty scale above 4 processors? For example, could crafty utilize all the >CPUs on an IBM pSeries 690 7040-681T 32-way? > >http://www-132.ibm.com/content/home/store_IBMPublicUSA/en_US/eServer/pSeries/high_end/690.html > >MH I didn't have time to look closely. But it is most likely a NUMA platform, which means that Crafty as it exists now is not going to work well on it. NUMA machines require careful attention to what is put where in memory, so that often-used data is as close to the physical processor (in terms of access latency) as possible. The current implementation of SMP in Crafty is based on pure SMP, where memory is simply shared. If I ever have time to fiddle with a NUMA machine, I'll probably look at fixing the major issue, which is to put split blocks close to each processor, and when giving a specific processor a tree to search, using a split block that is _close_ to it.
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