[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] xen 4.5.0 rtds scheduler perform poorly with 2vms
2015-11-29 11:18 GMT-05:00 Dario Faggioli <dario.faggioli@xxxxxxxxxx>: > > On Sun, 2015-11-29 at 04:46 -0800, Yu-An(Victor) Chen wrote: > > So st_jobs_stats for the missed deadline jobs are: > > > > trial #1 composed of 2 tasks: total tasks utilization rate = 1 > > > > (period, exe, deadline)=(21ms,12.023ms,21ms) -> miss all deadline > > (period, exe, deadline)=(100ms,37.985ms,100ms) -> no miss > > > > trial #2 composed of 2 tasks: total tasks utilization rate = 1 > > > > (period, exe, deadline)=(68ms,40.685ms,68ms) -> miss all deadline > > (period, exe, deadline)=(70ms,28.118ms,70ms) -> no miss > > > > trial #3 composed of 2 tasks: total tasks utilization rate = 1 > > > > (period, exe, deadline)=(16ms,11.613ms,16ms) -> miss all deadline > > (period, exe, deadline)=(46ms,12.612ms,46ms) -> no miss > > > The point is: how did you come up with these numbers? What both me and > Meng are trying to say is that the budget(s) and period(s) of the > (vCPU's of a) VM and the budgets and periods of the task running inside > the VM must fulfill certain relationships, or schedulability is not > something you can even hope for! :-/ > > > I do notice that for within the task that misses deadline, the > > completion time get progressively longer, > > for example: for trial #3, a snapshot of the task st_jobs_stats tells > > me that > > the completion time of the job is 79ms and then 87ms, and then 95ms > > > That depends on how missing a deadline is handled and accounted for. I > don't recall how Litmus^RT does that. LITMUS by default let the task keep running even when it misses deadline. But if users specify the enforce_budget (the name may be a little different), it will abandon the unfinished work at deadline miss. Meng -- ----------- Meng Xu PhD Student in Computer and Information Science University of Pennsylvania http://www.cis.upenn.edu/~mengxu/ _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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