Author: Eugene Nalimov
Date: 16:27:29 03/05/04
Go up one level in this thread
On March 05, 2004 at 19:03:56, Keith Evans wrote: >On March 05, 2004 at 08:51:27, Vincent Diepeveen wrote: > >>On March 05, 2004 at 08:47:24, Vincent Diepeveen wrote: >> >>>On March 04, 2004 at 13:28:53, Keith Evans wrote: >>> >>>>On March 04, 2004 at 12:42:24, Vincent Diepeveen wrote: >>>> >>>>>On March 04, 2004 at 09:44:00, Bryan Hofmann wrote: >>>>> >>>>>>On March 03, 2004 at 21:29:39, David B wrote: >>>>>> >>>>>>>I have a Tyan 2885 currently not sure if its a bios setting or just an OS >>>>>>>setting within Windows 2003 Enterprise Edition though its supposed to support >>>>>>>numa which to the life of me I can not get it to do. Each processor currently >>>>>>>is running 1gig of ram with Opteron 244's >>>>>>> >>>>>>>Thanks >>>>>> >>>>>>I recommend reading the following; >>>>>> >>>>>>http://www.tyan.com/support/html/f_s2885.html >>>>> >>>>>David, >>>>> >>>>>Except for DIEP which has NUMA versions, and SOS which is multiprocessing too, >>>>>but heavily relying upon shared memory, which program do you plan to run that >>>>>profits from a NUMA machine setup? >>>>> >>>>>Nevertheless in your manual from your tyan mainboard you can find how to get >>>>>numa to work. If i remember well the best thing to do is just fill up all memory >>>>>banks with memory. That's the best way to do it always. >>>> >>>>I understand that Crafty supports NUMA under Windows. >>> >>>All crafty does do is put a thread to a specific cpu. Though that is important >>>condition to run NUMA, it doesn't mean that all other stuff you need for NUMA >>>gets used. >>> >>>It's multithreading of course, so it's completely SMP in that respect. >>> >>>I've already explained it a dozen times here. Bob just claims it's NUMA, but he >>>has not even written the code himself, so he doesn't even know what he talks >>>about. >>> >>>I claim the dual opteron platform to be a better SMP platform than dual P4 Xeon >>>or dual K7. That it is NUMA too is just good for those who support NUMA. Crafty >>>in itself will NOT run at NUMA hardware like Origin3800 or Altix3000. >>> >>>There NUMA means the random latency from this processors memory to other >>>processors memory is *significant* slower than that of the SMP machines. >>> >>>So crafty is not NUMA at all. It doesn't run on NUMA machines other than the >>>only NUMA machine where SMP is faster than SMP at others. >>> >>>Best regards, >>>Vincent >> >>To run very well at a 8 processor Xeon, you need to be multiprocessor. >>So shredder all multithreading thoughts in advance. >> >>Diep runs well at 8 processor Xeon. SOS runs well. >> >>Crafty,Shredder,Fritz (the commercial version),Junior they run very bad at that >>hardware. >> >>Simply because they are multithreading. >> >>As Nalimov has shown you can in theory handicap multithreading to a form that it >>is more looking like multiprocessing than multithreading. >> >>That's not how it gets used in practice and sure not by crafty like that. You >>simply *need* to be multiprocessor. > >The poster was asking about an Opteron system. I think that we all know how well >Crafty runs on a quad Opteron system from CCT6. Just ignore Vincent's nonsense. First, original question was about NUMA system, not about "large NUMA system". Even dual-CPU Opteron is NUMA, and non-NUMA-aware SMP application can run badly there (due to the way cache coherence traffic is implemented). Second, (multithreading vs. multiprocessing) and (NUMA vs. SMP) are orthogonal issues. On NUMA systems you can have well tuned multithreaded applications as well as badly tuned multiprocessor applications. And third, Windows NUMA support in Crafty does not only "put a thread to a specific cpu". There is much more code there. From my experience on at least one large NUMA system Crafty runs reasonable well up to 16 CPUs (if we are talking about nps). There are some issues, and Bob would address them in the future, but I definitely cannot say "runs badly". Thanks, Eugene
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