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* Esben Nielsen <simlo@phys.au.dk> wrote: > Sorted lists works deterministicly O(1) on UP if no owner of the lock > blocks while having the lock. On SMP or worse if an owner blocks in > the lock, the wait list can grow very long. Thus insertion of new > elements takes a long time - with preemption disabled :-( the wait list can grow only as long as the max # of RT tasks is. Sorted lists become 'O(1)' if we added some code that globally limits the number of RT tasks to say 50. E.g. /proc/sys/kernel/max_nr_RT_tasks. A user can override it if he needs more RT tasks. There can be an arbitrary number of SCHED_OTHER tasks. (note that on Linux there is a RAM-dependent 'max # of tasks' ulimit which is never 'infinity', so theoretically the sorted lists are "O(1)" too. But this is nitpicking.) > If this is supposed to be used for user-space PI as well I would say > it would have to be completely bounded, i.e. plists are certainly > needed. [...] yes, it's supposed to be used for user-space PI too. What do you mean by 'completely bounded'. Do you consider the current worst-case O(100) property of plists a 'completely bounded' solution? i dont think fusyn's should be made available to non-RT tasks. If this restriction is preserved then fusyn's would become O(max_nr_RT_tasks) too. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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