Author: Robert Hyatt
Date: 06:35:54 03/27/01
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On March 27, 2001 at 08:17:43, Vincent Diepeveen wrote: >On March 26, 2001 at 22:44:53, Robert Hyatt wrote: > >>On March 26, 2001 at 20:54:48, Dan Andersson wrote: >> >>>I have to agree that multibanked memory and lage cashe size are very beneficial. >>>Those factors could very well explain the superlinearity. >>> >>>Regards Dan Andersson >> >> >>I don't think the 4-way interleaving helps. That _barely_ lets the machine >>hold its own, memory-wise, because there are 4x as many cpus fighting over >>access to memory... making it nearly 4x faster just barely breaks even. The >>larger L2 cache may well make a difference, of course... > >You speak for Crafty. I speak for DIEP. >I'm doing 8 probes of at least 16 bytes an entry. >that's 128 bytes. That still doesn't mean a thing. 4-way interleaving makes memory run 4x faster to fill a cache line. But since you have 4 cpus, you need 4x as many cache line fills. Which is a "wash". If there was no 4-way interleaving, you would see performance drop by a factor of 4 for most chess programs since they don't fit into L2. > >I also do that to get a possible evaluation out of hashtable as i store >evaluations in hashtable. > >So i do way more of those octo-probes as most progs try the hashtable... > >Further my whole program is made out of 'int'. So that means in short >that all kind of tables are 4 times bigger (in bytes) as they could >be. That means that when compared to some years ago i need quite some >accesses to main memory. > >Both the bigger L2 cache and the faster memory helps a lot then. > >Best Regards, >Vincent
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