* Esben Nielsen <[email protected]> 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 [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
