Author: Robert Hyatt
Date: 17:02:50 05/06/04
Go up one level in this thread
On May 06, 2004 at 19:03:48, martin fierz wrote: >aloha! > >bob posted some crafty logfiles running a 24-position test set on his ftp site >(for anyone else crazy enough to repeat what i did: >ftp.cis.uab.edu/pub/hyatt/smpdata) > >these are logfiles of crafty running as single CPU, dual, or quad; on opterons. >i took the last completed ply on the single CPU set for each position (marked by >-> in the logfile, i hope...), wrote down the time to complete this ply, and did >this for all logfiles. there are 9 of these, 4 repeats for 2 and 4 CPUs. i >computed the speedup for time-to-finish-ply-X for each of the multi-CPU runs >with the following results: > >2 CPUs: >1.961 +- 0.093 >1.888 +- 0.074 >1.846 +- 0.078 >1.763 +- 0.084 > >4 CPUs: >3.15 +- 0.15 >3.29 +- 0.20 >3.06 +- 0.12 >3.19 +- 0.13 > That is higher than my number although I only checked log 1 for mt=4. Did you compute the speedup for each position, then add and divide by 24? If so, I'm not a fan of that way. A long search on an efficient position skews the results. I prefer to take the total time for each run and use that... But either is "a number"... >now, is there any meaning to this, and if yes, what? > >point #1 to make is that the numbers here are mutually consistent with each >other, given the error margins quoted. which should show those skeptical of this >statistical approach that it makes sense to do it this way, rather than to just >write "i measured speedup 3.1". > >point #2 is that the speedup on 4 CPUs on average is 3.17 in this test, which >might be one point for bob in the duel with vincent; although i suspect that the >speedup depends on the hardware architecture - i will leave this question to the >parallel computing experts though... The opteron is not as good as a real SMP box. Such as my quad xeons. Opteron is NUMA which definitely has "issues" to deal with. > >point #3 is perhaps most important for the bob vs vincent duel: the standard >error for a 4 CPU test run is on the order of 0.2. if vincent's tests were with >a similarly small number of positions, then the differences measured in these >experiments (2.8 / 3.0 / 3.1) are statistically insignificant, and the whole >argument is pointless :-) I have said that 100 times. But let's see if you convince Vincent... > >cheers > martin > > >disclaimer: i computed the search time in seconds from crafty's log file by >converting minutes:seconds to seconds in my head. i may have made a mistake here >or there, although i did my best not to - but it's late at night and quite >boring to look through crafty logfiles...
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