forked from luck/tmp_suning_uos_patched
2eb1b12049
For SCHED_RR tasks we can do some really trivial timeslicing. Basically we fire up a time for every scheduler tick that searches for a higher or same priority thread that is on the runqueue and if there is one context switches to it. Because we can't lock spus from timer context we actually run this from a delayed runqueue instead of a timer. A nice optimization would be to skip the actual priority bitmap search when there are less contexts than physical spus available. To implement this I need a so far unpublished patch from Andre, and it will be added after we have that patch in. Note that right now we only do the time slicing for SCHED_RR tasks. The code would work for SCHED_OTHER tasks aswell, but their prio value is defered from the one the PPU thread has at time of spu_run, and using this for spu scheduling decisions would make the code very unfair. SCHED_OTHER support will be enabled once we the spu scheduler knows how to calculcate cpu_context.prio (very soon) Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com> |
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