Author: Robert Hyatt
Date: 05:14:30 08/11/98
Go up one level in this thread
On August 11, 1998 at 08:06:36, Tom Kerrigan wrote: >Aside from software differences, the Pentium MMX/200 has a 66MHz L2 cache >(possibly smaller than 512k) whereas the Pentium II/300 has a 512k 150MHz L2 >cache. If a program really bangs on the L2 cache, it will go much faster on the >Pentium II. > >Cheers, >Tom > >On August 10, 1998 at 22:23:46, fca wrote: > >>I am puzzled, Uri. >>http://www.rebel.nl/bench.htm shows the P2/300 about 50% - 60% faster than the >>P200MMX for Rebel. >>Intel benchmark pages ( SPECint (base)95 ) give +80%. >>While obviously different programs benefit by different amounts by CPU upgrades, >>your figures show +150% which is a huge difference! >>Any ideas? Besides Tom's comment about Cache, there are other issues. The original pentium had a serious design flaw in the pipieline that would let one pipe stall far more than necessary. This was corrected in the MMX versions. Also the original pentium had a horrible bug in branch prediction, and would perform poorly on programs with lots of branches (A chess program typically falls in this category because of all the if...then...else... cases in the evaluation. The MMX also fixed this bug. So such a big jump on a poorly-behaved program is not a surprise. The typical benchmark program is much better behaved than a chess program, with far fewer branches, and more regular memory references. Chess programs are pretty bad actors and stress hardware... this is one reason that it seems that Crafty is going to be in the new SpecInt98 benchmark... it will be the first 64 bit integer program and the first non-numerical algorithm that will really stress- test compiler optimizers...
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.