Author: Matt Taylor
Date: 12:27:31 12/17/02
Go up one level in this thread
On December 17, 2002 at 15:19:34, Robert Hyatt wrote: >On December 17, 2002 at 14:21:10, Gian-Carlo Pascutto wrote: > >>On December 17, 2002 at 13:15:36, Robert Hyatt wrote: >> >>>On December 17, 2002 at 11:58:21, Gian-Carlo Pascutto wrote: >>> >>>>On December 17, 2002 at 11:27:18, Matt Taylor wrote: >>>> >>>>>Crafty gets better results with HT, >>>> >>>>In addition to what Vincent said, the data we currently >>>>have is saying exactly the opposite. >>>> >>> >>>I don't follow. I posted the following twice already: >> >>I've done my own tests. >> >>>1 thread, SMT disabled, 24 positions, run twice, 1001.5K nps >>>2 threads, SMT disabled, same conditions, 1604.5K nps >>>3 threads, SMT enabled, same conditions, 1820.25K nps >>>4 threads, SMT enabled, same conditions, 1923.0K nps >>> >>>Hyperthreading took the 16.04.5K nps for two bare xeon processors and >>>improved that by 20%. I can certainly post the raw data if it is important. >>>I believe 20% is definitely better than 11%. And 20% is not something to wave >>>off as unimportant. >> >>I measured similar numbers for 1->2 cpus (24%). But this is only >>NPS increase, not the actual speedup which will be lower. > >So? That's outside the scope of the SMT/HT discussion. The question is "does >it >work" not "does it work well for chess applications." > >>-- >>GCP Intel claims 30-40% for the former. Dr. Hyatt claims about 20% for the latter. Vincent claims 11% for the latter. Eugene reports some things going 100% faster. The question of which application is entirely relevant for obvious reasons. In the general case, most things will benefit. Whether or not they benefit -much- is different, but it doesn't really matter. HT isn't costing Intel more than pocket change to add to the CPU. Even a 1% speed gain for a dollar isn't too bad. It's just unfortunate that you can't buy CPUs on that curve. AthlonXP 2100 = $85. If only you could double performance for an extra $100! All an extra $100 gets you is AthlonXP 2400. -Matt
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