Yes, it was precisely because of an outbreak of '-177 Maximum Elapsed Time Exceeded' errors that Dagorath asked me to visit the project and try to help troubleshoot.
http://numberfields.asu.edu/NumberFields/forum_thread.php?id=35&nowrap=true#283 ----- Original Message ----- From: Travis Desell To: Richard Haselgrove Cc: BOINC Developers Mailing List Sent: Monday, November 07, 2011 6:53 PM Subject: Re: [boinc_dev] APR, DCF and non-deterministic projects We've had similar issues with the n-body simulations we're doing on milkyway@home. The runtime of the workunits is fairly dependent on the initial random distribution of bodies, and the runtimes can vary from a couple hours to a couple days. It would be nice to get away from having to specify the RSC_FPOPS_EST for each workunit, especially as in our case it can cause workunits to be terminated prematurely by the clients. I don't suppose you've run into this problem as well? On Nov 7, 2011, at 12:25 PM, Richard Haselgrove wrote: Part 2 of this research: Credit Because the NumberFields tasks are so variable (from 2 ro 300,000 seconds), I've been looking at the rate that credit has been awarded - Credits per hour (of runtime) gives a nice human-scale value. Here are the results for my four hosts at NumberFields. All four were attached at the same time (note the consecutive HostIDs): in particular, the two Q6600 hosts have identical hardware. http://img46.imageshack.us/img46/826/numberfieldscreditperho.png The problem is that the rate at which credit is granted depends critically on the host APR value. With a non-deterministic project, especially in the early days after attachment, APR is heavily influenced by the random processing time of the early tasks. The credit/hour for all hosts were tightly grouped for the first 10 tasks, when APR is effectively ignored, but thereafter they diverge spectacularly. Hosts 1288 and 1289 happened to get short tasks first, so APR was artificially high when it was first used for credit calculation: hosts 1290 and 1291 happened to draw longer-running tasks. It was host 1290 which received the 300,000 second task (http://numberfields.asu.edu/NumberFields/result.php?resultid=292439), and was awarded 4,500 credits (in round figures). At very much the same time, the identical host 1291 returned http://numberfields.asu.edu/NumberFields/result.php?resultid=317447, getting almost the same credit for just 43,000 seconds of work. It's discrepancies like that which lead users, and project administrators, to distrust CreditNew. I think it needs more work, especially if BOINC is going to continue to support non-deterministic projects. _______________________________________________ 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. --------------------------------------------------------------------------- Travis Desell, Assistant Professor University of North Dakota - Dept. of Computer Science [email protected] - cell: 518-867-1054 Streibel Hall Room 220 - office: 777-701-3477 3950 Campus Road Stop 9015 Grand Forks, North Dakota 52802-9015 Homepage ( http://people.cs.und.edu/~tdesell/ ) MilkyWay@Home ( http://milkyway.cs.rpi.edu/ ) DNA@Home ( http://dnahome.cs.rpi.edu/ ) Worldwide Computing Laboratory ( http://wcl.cs.rpi.edu/ ) ---------------------------------------------------------------------------- _______________________________________________ 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.
