On Oct 1, 2009, at 3:54 AM, Richard Haselgrove wrote: > Paul D. Buck wrote > >> The problem is that Eric's script will mean that over a 4 year life >> of >> a computer the CS it earns in year four will take more processing >> time >> to obtain. That is the flaw ... as the performance average increases >> the award goes down. So the CS I earned when I started BOINC 5-6 >> years ago, what ever it was, took less processing power over time >> than >> the same CS today (all other things being equal). > > I'm not 100% sure, but I *think* that is a mis-reading of the > purpose and behaviour of Eric's script. > > The script compares the credit awarded to the current cohort of > machines under that project's active credit-scoring scheme (flop > counting, in the case of SETI), with the credit that would be > awarded to the *same* cohort of machines under the benchmark*time > 'cobblestone' scheme. Then adjusts accordingly, with smoothing and > median-taking to reduce the effect of outliers. > > So, Eric's script will *not* alter the value of the cobblestone over > time merely because machines get, on average, faster: in principle, > both flopcounts and benchmarks should increase in proportion. > > In practice, architectural changes and more efficient processor > designs will mean that flopcounts increase more rapidly than > benchmarks with technological advances (already evident in the > different flop / benchmark ratios of Intel and AMD processors). So > Paul's predicted behaviour is real, but it's a second-order effect > and *not* an automatic, deliberate, design intention of the script. > > The other problem with the script is that will be thrown into total > confusion if GPU processing ever approaches the median. At the time > Eric wrote it, neither elapsed time nor GPU speed was available in > the result table, so a _G_PU result would be compared against _C_PU > time and _C_PU benchmark! Not pretty. I don't know of Eric has had > time to consider how to include the (very new) recorded GPU metrics > in the script, but it needs to be on the to-do list if the script is > going to be considered for wider long-term use.
I did not say it was the only purpose, but it has that effect ... I did not do the research so I don't know how profound the effect is ... And though I don't recall the exact wording of his note when he described the script on the SaH boards he said it would do this ... I would look it up for you ... but aside for answering Rastmer I am done with it ... Oh, and we are a year in with CUDA and the script is still not updated? Sorry ... that makes a mockery of maintenance ... and of the efforts of the participants ... _______________________________________________ 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.
