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Subject: Re: Crafty SMP questions.

Author: Slater Wold

Date: 21:23:22 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...

I don't know about the others...but I'm sold.  ;)



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