Author: Brian Richardson
Date: 08:01:12 06/20/02
Go up one level in this thread
On June 19, 2002 at 23:24:23, Robert Hyatt wrote: >On June 19, 2002 at 22:03:07, Brian Richardson wrote: > >>Alpha >>1 cpu 21264/600mhz: >>total positions searched.......... 300 >>number right...................... 300 >>number wrong...................... 0 >>percentage right.................. 100 >>percentage wrong.................. 0 >>total nodes searched.............. 236973211.0 >>average search depth.............. 4.5 >>nodes per second.................. 783641 >> >>2 cpus, 21264/600mhz: >>total positions searched.......... 300 >>number right...................... 300 >>number wrong...................... 0 >>percentage right.................. 100 >>percentage wrong.................. 0 >>total nodes searched.............. 330905102.0 >>average search depth.............. 4.5 >>nodes per second.................. 1266767 >> >>AMD 1900+MP >>max threads set to 2 >>hash table memory = 384M bytes. >>pawn hash table memory = 32M bytes. >>pondering disabled. >>Crafty v16.19 (2 cpus) >>test results summary: >>total positions searched.......... 300 >>number right...................... 300 >>number wrong...................... 0 >>percentage right.................. 100 >>percentage wrong.................. 0 >>total nodes searched.............. 19013488028.0 >>average search depth.............. 12.2 >>nodes per second.................. 1357144 >>(run without test xxx n, st=60) >> >>1 CPU >>total positions searched.......... 300 >>number right...................... 300 >>number wrong...................... 0 >>percentage right.................. 100 >>percentage wrong.................. 0 >>total nodes searched..............4639292700.0 >>average search depth.............. 9.7 >>nodes per second.................. 960490 >>(run with test xxx n=8) > > >I am _totally_ confused now. The alpha did 800K with 1 cpu, 1200K with >two. We discovered the "locking" problem and eliminated it, which made >the NPS scale like it should later. The 2 cpu = 1.5x faster was a clue >in that NPS (for crafty) scales linearly with number of processors, although >search overhead makes some of that NPS wasted. > >For your results, your 1 cpu number is 960K and your two cpu result >is 1300K. That doesn't look reasonable. And AMD dual should see the >NPS almost exactly double using two cpus. > >Can you clarify your numbers above or am I mis-reading??? I have a hunch about what might be going on. The Alpha results above show an average search depth of 4.5, which means the test xxx n command (n is stop each test after n plys correct) was probably used with n=2 (per your other email and a test I also ran). I suspect this runs each test for a much shorter time than the longer runs, which results in significantly lower average nps results for the entire suite, given other overhead. I also think this is behind the AMD scaling looking relatively poor, since the 2 CPU run was with just st=60 and no "n", which takes 5-6 hours, and the 1 CPU result which was one I tried to do "quickly" last night with n=8 (after observing odd results with an n=2 run). All of this is with version 16.19, which of course does not have the xor lockless hashing. It is probably not worthwhile going much further, since reproducing Alpha results would be difficult. My feeling at this point is that AMD today is roughly comparable to older Alphas, but either way I still believe 64 bits is the way to go. Brian
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.