Messages in this thread | | | Date | Wed, 27 Jul 2005 11:09:08 -0500 | From | "K.R. Foley" <> | Subject | Re: [RFC][PATCH] Make MAX_RT_PRIO and MAX_USER_RT_PRIO configurable |
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Esben Nielsen wrote: > On Wed, 27 Jul 2005, Ingo Molnar wrote: > > >>* Steven Rostedt <rostedt@goodmis.org> wrote: >> >> >>>Perfectly understood. I've had two customers ask me to increase the >>>priorities for them, but those where custom kernels, and a config >>>option wasn't necessary. But since I've had customers asking, I >>>thought that this might be something that others want. But I deal >>>with a niche market, and what my customers want might not be what >>>everyone wants. (hence the RFC in the subject). >>> >>>So if there are others out there that would prefer to change their >>>priority ranges, speak now otherwise this patch will go by the waste >>>side. >> >>i'm not excluding that this will become necessary in the future. We >>should also add the safety check to sched.h - all i'm suggesting is to >>not make it a .config option just now, because that tends to be fiddled >>with. >> > > Isn't there a way to mark it "warning! warning! dangerous!" ? > > Anyway: I think 100 RT priorities is way overkill - and slowing things > down by making the scheduler checking more empty slots in the runqueue. > Default ought to be 10. In practise it will be very hard to have > a task at the lower RT priority behaving real-time with 99 higher > priority tasks around. I find it hard to believe that somebody has an RT > app needing more than 10 priorities and can't do with RR or FIFO > scheduling within a fewer number of prorities. > > Esben >
Actually, is it really that slow to search a bitmap for a slot that needs processing? I work on real-time test stands which are less of an embedded system and more of a real Unix system that require determinism. It is very nice in some cases to have more than 10 RT priorities to work with.
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