Author: Vincent Diepeveen
Date: 08:49:31 12/31/02
Go up one level in this thread
On December 30, 2002 at 22:32:52, Robert Hyatt wrote: >On December 30, 2002 at 20:29:11, Vincent Diepeveen wrote: > >>On December 30, 2002 at 19:39:23, Frank Koenig wrote: >> >>>Two questions. >>> >>>One) Will Intel's HT technology be able to help chess programs above and beyond >>>just allowing one CPU to appear as two? >>> >>>Second) If you are running XP, will HT require XP Pro instead of XP Home to take >>>advantage of it? >>> >>>Thanks, >>> >>>Frank >> >>For dual machines you need even newer releases of OSes to still get >>released. >> >>However you can profit from it in a very limited way. It's a speedup of >>18% for DIEP at the latest P4 (3.06Ghz), at older P4s the profit is less >>(like P4 Xeon 2.8Ghz) and even older P4s the profit is zero or negative. > >Any chance you will _ever_ "test before talking"? > >The 2.8 xeon has the _same_ SMT core as the PIV/3.06. The _same_ means >"the same", not "something that is not as good as." http://www.realworldtech.com/index.cfm and ask intel designers themselves. >That is simply a crock statement that is nonsense. From _testing_ on >my part... I see a clear difference in performance. Intel managed to slowly improve SMT to what it is now. I do not find 18% impressive knowing the chip is already that much slower than the K7 for me. > >> >>So it's progressing but the P4 is a processor not really mature enough: >>too little trace cache and too little datacache: just 1024 quadwords; > > >So? 12K micro-ops. 8kb data. Core-speed L2 cache with 512KB unified >cache. Seems to work quite well in all the testing I have done. If it is in theory simply 2 processors then 11% at older types and 18% at new P4 3.06ghz is not much and because of the small L1. Also i didn't figure out yet how big the branch prediction table (BTB) is in the P4 but it probably isn't so impressive. > > >>compare with the 64KB L1 data cache of a K7 which is i guess 16384 >>doublewords. > > >what is with all the quadword/doubleword nonsense? >I think _most_ here can figure out what 64 KB turns into in your favorite >data size... 64KB of K7 and just 1024 words of P4. The P4 is using 64 bits adressing for the L1 that means just 1024 words. I prefer personally 16384 words of 32 bits. However the P4 doesn't deliver 2048 words of 32 bits. It delivers 1024 words of 64 bits. > > > >> >>It's already having a very small L1 cache and trace cache compared to >>the L1 of the K7 (128KB) and now you have to divide that by 2 again. >> >>So that isn't very positive yet. >> >>Let's wait for the future if we can see bigger profits. In which case it >>gets very interesting of course.
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