Messages in this thread | | | Date | Sat, 3 Nov 2007 19:16:42 +0100 | From | Andi Kleen <> | Subject | Re: [PATCH 5/6] sched: SCHED_FIFO/SCHED_RR watchdog timer |
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On Wed, Oct 31, 2007 at 11:03:28PM +0100, Peter Zijlstra wrote: > > On Wed, 2007-10-31 at 22:49 +0100, Andi Kleen wrote: > > Peter Zijlstra <a.p.zijlstra@chello.nl> writes: > > > > > Introduce a new rlimit that allows the user to set a runtime timeout > > > on real-time tasks. Once this limit is exceeded the task will receive > > > SIGXCPU. > > > > Nice idea. > > > > It would be even nicer if you could allow a couple of them. Partition > > the RT priorities into a few classes and have an own limit for each them. > > > > A small number of classes (3-4) would be probably enough and not bloat > > the rlimits too much. > > > > I'm thinking of the case where you have different kinds of real > > time processes. Like your mp3 player which you want to be slightly > > real time, but with a low SIGXCPU limit. > > > > And then something else real time which is more important and > > you would set a higher limit. etc. > > But its an rlimit, it can be set per process. Not sure what multiple
That's impractical -- you would need to patch the process or call it from a special program, which is not nice.
rlimits are useful to set a limit during log in. For that the children can be all kinds of different processes and possibly use different settings.
> classes per process would gain us, let alone how that process has to > figure out which class to use.
You set the classes once per rlimit (e.g. in a pam module) Then the processes set different scheduling priorities by themselves (standard programs do that). Then that priority would map to a different class.
-Andi
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