On Apr 27, 2009, at 5:47 AM, [email protected] wrote: > Deadlines can be SHORTER THAN AN HOUR. There have been projects with > deadlines of 5 MINUTES. > > I know I have stated this before.
And I know that I have stated this before. Sending tasks out to a uncontrolled system like BOINC with deadlines of this nature is insanity. Likewise, it is insanity to drive all policy with an outlier project like this if we also don't allow and controls to policy for other exceptions. Like, don't interrupt work in progress unless you have an emergency like this ... and only then ... not for made up emergencies ... Worse, most of the exceptions that are dragged out as examples lead to rules that cause the systems to behave in very bad ways. I have 7 VTU tasks running right now, all with 10 more minutes to run 56% complete and a deadline of the 29th, meaning that this precious 5 minute deadline maker rule is causing BOINC to over react and run tasks in parallel where there is no need. Even granting the need, these tasks have plenty of time to run in serial mode and none at all to have started off in high priority mode. As far as the frequency, ok, fine 5 minute task deadlines, the tasks better damn well be 2 bytes long with a 10 second run time because there is no other way that a task like that can be guarenteed a 5 minute turn around even on my fastest system with download, run, upload if it has any sort of real work to do. And by the way, which project has these tasks? I have never seen it yet ... The problem with accepting the argument that using event driven logic, is that if the frequency of the events gets high enough the system will become unstable. In the hypothetical 5 minute deadline I can buy scheduling the task... if it is 2 days in the future, no ... the problem is that there is no distinction... and the event driven model means that a higher and higher percentage of time is going to be taken up by this frenetic activity. And because BOINC recalculates everything fresh it is always going to change its mind ... and the faster the systems get with more processing elements the frequency is going to keep climbing. A dual Xeon with 16 CPUs and 3 GTX 295 cards is a total of 22 processing units ... using this event based model I can easily believe that the frequency will be down to about once per second ... so which project has a deadline 5 seconds in the future? Well, my VTU shock wave passed and sure enough, BOINC started one new task out of all that ... so a task that BOINC considered vital to run a little while ago is now going to languish like a dead mongoose while I wait for it to worry about it again ... _______________________________________________ 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.
