Messages in this thread | | | Subject | Re: [PATCH] [request for inclusion] Realtime LSM | From | Lee Revell <> | Date | Wed, 05 Jan 2005 10:21:11 -0500 |
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On Wed, 2005-01-05 at 12:52 +0100, Ingo Molnar wrote: > the RT-LSM thing is a bit dangerous because it doesnt really protect > against a runaway, buggy app. So i think the right way to approach this > problem is to not apply RT-LSM for the time being, but to provide an > 'advanced latency needs' scheduling class that is _still_ safe even if > the task is runaway, but behaves with near-RT priorities if the task is > 'nice' (i.e. doesnt use up large amount of CPU time.) > > incidentally, there is such a scheduling class already: negative nice > levels. Please skip any preconceptions you might have about nice levels, > nice levels have been improved in 2.6.10, the timeslices are now given > out exponentially, giving nice -20 tasks far more weight and priority > than they used to have. (They are obviously still preemptable if they > keep looping burning CPU - but that we can consider a feature.) (Also, > in 2.6 the negative nice levels have a much more agressive interactivity > setting, allowing them to preempt everything lower-prio.) > > so, could you try vanilla 2.6.10 (without LSM and without jackd running > with RT priorities), with jackd set to nice -20? Make sure the > jack-client process gets this priority too. Best to achieve this is to > renice a shell to -20 and start up everything from there - the nice > settings will be inherited. How does such an audio test compare to a > test done with jackd running at SCHED_FIFO with RT priority 1? > > if this works out well then we could achieve something comparable to > RT-LSM, via nice levels alone.
Ugh, screwed up the cc: list. Sorry for the WOB.
Paul, care to comment on the above?
Lee
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