Author: Matthew Hull
Date: 21:34:40 08/05/03
Go up one level in this thread
On August 06, 2003 at 00:21:09, Robert Hyatt wrote: >On August 06, 2003 at 00:09:32, Slater Wold wrote: > >>On August 05, 2003 at 23:54:42, Slater Wold wrote: >> >>>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. >> >>Oh, and..."Pricing for the p690 starts at US$493,386 with an eight-way >>configuration featuring Power4+ 1.5 GHz processors, 8 GB of main memory and two >>36 GB disk drives with AIX preinstalled." >> >>Starts...at...half...a...million...dollars... >> >>That's about $62k per CPU+1GB RAM. Take off 10% for each CPU+1GB RAM. >> >>Add 24 CPUs, then add 24GB RAM. You're at somewhere around $2M. > > >at that price it _could_ be a real SMP platform... > >And Crafty _should_ scale just fine on it... It looks like an MCM will use memory interleaving for pure SMP. An MCM can have up to 8 processors in it. A 32-way has 4 MCMs. But I would assume that a 32-way is just 4 8-ways just like and 8-way Xeon is just two 4-ways. MH
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