Author: Vincent Diepeveen
Date: 08:11:52 04/10/03
Go up one level in this thread
On April 10, 2003 at 11:07:06, Robert Hyatt wrote: >On April 10, 2003 at 08:44:18, Vincent Diepeveen wrote: > >>On April 09, 2003 at 17:58:21, Robert Hyatt wrote: >> >>as usual you were asleep when replying. i did math for a single cpu. that >>extrapolates to more cpu's as well. > >I did math that extrapolates to _everything_. > >If I get 1.7X speedup for two cpus, I will get _some_ speedup no matter how slow >the >second processor is. > >Which was my point. with SMT that is not the case. the second cpu in SMT delivers somewhere between 0% and 20%. If it is 10% like it is for most programs then: 1.1 speed is what you get out of single P4 with smt. 1.7 / 2 * 1.1 = 0.935 which is slower than single cpu. Which is my point. > >> >>If you first slowdown crafty in order to then get a better speedup from SMT >>that's your choice. > >I didn't "first slowdown crafty". The SMP version runs just as fast as the >non-SMP >version, so I have no idea what you are talking about... > > >> >>>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
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