Good comment already given from Raistmer and Paul.
Another view in reply: Lynn W. Taylor wrote: > This will be my final post on the subject. > > To take the clock analogy one step further. > > You're saying that your cesium clock is much better than the cheezy $1 > westclox wind up I got at the local bargain shop. > > ... and I'm saying that the cobblestone standard explicitly calls for > the use of a wind-up clock. > > I agree with everything you've said. I agree that Whetstones and > Dhrystones are not the best predictors of performance. Indeed so, we agree on that as the present situation. > But the standard says "you put the dhrystone number for your machine > here, and you put the whetstone number for your machine here, and you > put the number of CPU seconds here, and that's your credit, in > cobblestones." And that is the "religious" what 'is', is. Amen. Or we can be scientific and say that was a good first approximation that served it's purpose well enough. We can now move on and do better. > Martin wrote: >> Lynn W. Taylor wrote: [...] >>> .... starting with the fact that we aren't directly calculating >>> cobblestones. >> >> A little of the architectural influence can be read from a recent >> comparison article: >> >> http://www.tomshardware.com/reviews/athlon-l3-cache,2416.html [...] >> >> Note in the benchmarks the identical dhrystone scores and yet some of >> the tests can show as much as a 20% real world performance difference. >> >> So... Do we put +/- 20% error bars on the credits cobblestones >> "depending" on 'whatever'... And that's before allowing for any >> approximations made for the FLOPs count for the s...@h-wu AR. Is +/-20% near enough even for a bit of "fun"? I suspect various (non-FLOPs) Boinc projects will see even worse than that... I'll close on this well thrashed thread that I don't care about credits-as-bragging-rights, at all. I will admit that my scientific sensibilities are badly irked by various non-FLOPs projects needing to award arbitrary credit according to such occultism as to how tea leaves might settle in the bottom of a morning brew. Credits or scientific discredit? However, a useful measure of performance for comparison would be, well, useful. If only to be able to authoritatively claim that Boinc is equivalent to X supercomputers for a specific task. We can't reliably assume processing effort as "credits = f( CPU time )" for unknown hosts. Especially so when those hosts are multitasking, or "hyper threaded", or even a virtual host lost in virtualisation. Some OSes do not even reliably report time. Further, the benchmarks are completely non-representative for GPUs. Hence, I still put forward my vote for awarding credits for a WU by hierarchical calibration back to physical known hardware, our "Etalon" computer. Happy crunchin', Martin ( Good thread :-) ) -- -------------------- Martin Lomas m_boincdev ml1 co uk.ddSPAM.dd -------------------- _______________________________________________ boinc_dev mailing list [email protected] http://lists.ssl.berkeley.edu/mailman/listinfo/boinc_dev To unsubscribe, visit the above URL and (near bottom of page) enter your email address.
