Why aren't tasks run in deadline order?
16 Jan 2012 4:14:34 UTC
Topic 196139
(moderation:
I've been receiving some massive tasks that are estimated to take up to 34 hours to complete. Tasks do not run in deadline order so sometimes it doesn't even start a task until it's too late for it to finish in time. Also, it seems to randomly jump among tasks with as many as four having partial progress.
Is there some way to control the processing order? Whatever priority is being set internally simply does not work well.
Mac OS 10.6.8
BOINC 6.10.43
Why aren't tasks run in deadline order?
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When BOINC does not calculate itself to be in danger of missing a deadline, I believe it processes units within a project in the order they were downloaded. So long as you set a work queue short enough to allow for variations in estimation and in your own offering of your host for BOINC work, this usually works well enough.
Sadly, when it does think itself in danger of missing deadline (often wrongly), the choice of work to run seems to many of us downright whimsical, verging to counterproductive. Specifically the behavior of starting a task, then suspending it after some work is accomplished in favor of one with a yet later deadline. I've personally seen this to lead to dozens of suspended partially completed tasks on a single host.
You can do two things. By far the most helpful it to set a low queue length request (under computing preferences, the sum of the "Computer is connected to the Internet about every" entry and the "Maintain enough work for an additional" entry, the web version for your host's location (a.k.a. venue), or your local host version if you are using local preferences).
Less helpful, but more directly responsive to your question as posed, you can set "no new tasks" on the project tab of BOINCmgr, then suspend all currently downloaded tasks for a project in trouble save the one you want to run--or possibly a very few more.
This second trick is best used to work one's way out of difficulty having already set a low (try a couple of hours at first) queue length.
Once BOINC learns how fast your host really is, and your usage habits, you may likely be able to increase the queue, perhaps substantially if you have a very simple work mix, or not so much if you have a toxic mix of faster than expected and slower than expected work (as arises from multiple task types on the same project for which the relative execution speed on your particular hardware does not match the model).
I'm sorry but I'm not totally
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I'm sorry but I'm not totally understanding your reply. Perhaps it's because you've described items in the Windows version? The closest thing I can find to "Maintain enough work for an additional" is "Additional work buffer" which I have set at 5 days. I keep it high because my primary project choice is SETI and they seem to have a LOT of server down time. If it's not kept high then the task(s) run dry -- sometimes for days. Their long downtime a year ago Thanksgiving is what started me doing Einstein.
I didn't realize individual tasks could be suspended so that was very good info. Whimsical seems a fitting way to describe the priorities. BOINC seems to have a handle on my computer's speed as the completion estimates are usually very close. I let BOINC run at all times unless the CPU tops 90% and I haven't seen that happen.
Guess I'll just keep an eye on it and manually nudge it in the right direction. It currently has partial work done on tasks due Jan 22, 25 & 28 but hasn't even started work on two 13-hour tasks that are both due on the 21st. (sigh)
Thanks for your help.
RE: The closest thing I can
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I copied and pasted the exact language for these items on the Einstein user account web page.
The language you quote is found on the Boincmgr preferences at the network usage tab. If you activate this local host preference, it takes precedence over your overall web-interface invoked setting.
While I can't judge for you how the differing benefits net out for your situation, I'll guess you'll want to continue your high queue length. If you'd like to avoid the problem that caused you to post, you may consider a form of manual throttling--by setting Einstein to No New Tasks most of the time, and just temporarily allow some download now and again--using the suspend feature if needed to cope with an awkwardly large download.
For a further option, you may wish to regulate which types of tasks you allow Einstein to assign to your host. On your Einstein account web pages, go to Your Account|Einstein@Home preferences Then find the location (a.k.a. venue) to which your host is assigned (if in doubt, check it on the Einstein web page listing your computers), and choose edit for that location--change the choices in the "run only selected applications" list. By deselecting the Binary Radio Pulsar item you'll avoid future downloads of the one which recently cost you over 59,000 CPU seconds.