Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Gilles Chanteperdrix wrote: >>> Jan Kiszka wrote: >>>> Andreas Glatz wrote: >>>>> Hi Philippe, >>>>> >>>>> At the Xenomai Users Meeting last year I asked you if Xenomai would offer >>>>> a possibility to lower the priority of certain Xenomai tasks below that >>>>> of Linux. We need this feature since we have tasks in our RT application >>>>> which should only run when Linux is idle (A statistics collection task >>>>> which part of the RT application and hard to isolate from this >>>>> application). >>>>> >>>> What prevents using a borderline thread (if you need to interact with >>>> blocking Xenomai services) with SCHED_OTHER and a Linux nice level of 19? >>> Well, this does not really guarantee that the thread will run only when >>> linux is idle. The thread will eat some cpu time, the nice level is not >>> a strict priority, as you know. >> Where do you really need anything stricter? It's the opposite of "I need >> true 100% CPU for my task, and that forever." >> >>> But in fact, I wonder why Andreas wants >>> a new scheduling policy for xenomai, what is needed, is simply a >>> SCHED_IDLE (maybe it exists ?!) policy for Linux. >>> >> There is no such thing AFAIK. If you are concerned that some CPU >> intensive low prio job eats too much CPU, you normally reduce its >> nice-level and/or confine its CPU bandwidth via cgroups. > > SCHED_IDLE exists. >
Ah, as "nice 20". Same mechanism, just another level. Jan
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