Author: Slater Wold
Date: 20:54:42 08/05/03
Go up one level in this thread
On August 05, 2003 at 20:00:44, Robert Hyatt wrote: >On August 05, 2003 at 19:13:21, Slater Wold wrote: > >>On August 05, 2003 at 18:38:51, Robert Hyatt wrote: >> >>>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. >> >>I really don't think it is a NUMA machine. >> >>"Advanced symmetric multiprocessing (SMP) up to 32-way", is how the exactly >>describe it. >> >>And when you go to their 'Clusters' section, this machine isn't mentioned. > > >NUMA is not necessarily a "cluster". There are several machines that are >called "SMP" but also use a NUMA approach for memory. The clue is the price. >A real 32-way shared memory system is _really_ expensive. Cray claimed that >50+% of the price of the T932 was in the memory interconnect to support full >memory speed to all processors. > >Of course, I'm not wagering anything on this "hip shot" as to the idea behind >the machine, but from what I have seen in past years, anything beyond 8 CPUS >is either _way_ expensive, or NUMA. Sorry, I mispoke myself....scratch that, let's try again. Reading http://www-1.ibm.com/servers/eserver/pseries/hardware/whitepapers/p690_config.pdf, it would appear that it is a true SMP system. IBM has their own way of doing things, using MCMs and such, with the GX controllers. 32 64-bit 1.7Ghz POWER4+ CPUs, 512GB RAM, and Crafty 19.04. Whew.
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