Author: Robert Hyatt
Date: 14:58:21 04/09/03
Go up one level in this thread
On April 09, 2003 at 17:02:34, Vincent Diepeveen wrote: >On April 09, 2003 at 11:52:48, Charles Worthington wrote: > >it shows that SMT is still in its childhood with the current P4s. Getting a % or >10 in nps speed from hyperthreading is not enough to get a positive speedup. > >Consider this. > >suppose fritz gets 1.7 speedup out of 2 processors. >suppose hyperthreading speeds up 10%. > >Then what is actual speedup? > 1.0 * 1.10 (speedup) * (1.7 / 2.0) = 0.935 which is SLOWER than 1.0 without. > >Easy math. > Poor math. If it gets 1.7 out of a dual, and the single cpu version does 1M nodes per second, and hyper-threading brings that to 1.3M, then the effective speedup will .7 of that extra 30% which turns into 1.21 X faster in terms of time to solution. That does assume that SMT makes his raw speed 1.3X faster, and that with two equal processors his speedup is 1.7. Your math is bad. >>I ran the Deepfritzmark and Shreddermark tests with hyperthreading disabled then >>enabled with some very confusing results that I am hoping someone can help >>explain: >> >>Test set #1 Hyperthreading Disabled, 64MB Hash, Engine Parameters @ default >> >>Shredder 7.04: Shreddermark: 2227 +- 0 (1.5s) 705kN/s >> >>Deep Fritz 7 : Deepfritzmark: 2724 +- 44 (3.1s) 2252kN/s >> >> >> >> >>Test set #2 Hyperthreading Enabled, 64MB Hash, Engine Parameters @ Default >> >>Shredder 7.04: Shreddermark: 2227 +- 0 (1.5s) 803kN/s >> >>Deep Fritz 7 : Deepfritzmark: 2476 +- 0 (3.2s) 2555kN/s >> >> >> >>Test set #3: Hyperthreading Enabled, 32 MB Hash, Engine Parameters @ Default >> >>Shredder 7.04: Shreddermark: 2784 +- 0 (0.4s) 907kN/s >> >>Deep Fritz 7: Deepfritzmark: 2476 +- 0 (3.4s) 2532kN/s >> >> >> >>Test set #4; Hyperthreading enabled, 16MB Hash, engine parameters @ default >> >>Shredder 7.04; Shreddermark: 2784 +- 0 (0.4s) 1008kN/s >> >>Deep fritz 7: Deepfritzmark: 2476 +- 0 (4.5s) 2544 kN/s >> >> >> >>This is somewhat confusing as Fritz scored the highest fritzmark with >>hyperthreading_disabled_ even though his kN/s were_far_lower. Shredder scored >>far better with it_enabled_ both in result, speed, and time to solution. >>Also Shredder seemed to benefit more from the smaller hash sizes where Fritz >>seemed relatively worsened by them. Does anyone have any insight as to these >>seemingly contradictory results? And would I be better to run Deep Fritz with >>the hyperthreading diasabled even though his kN/s is considerably lower? >> >>Charles
This page took 0.07 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.