• Christoph Hellwig's avatar
    [POWERPC] spu sched: static timeslicing for SCHED_RR contexts · 2eb1b120
    Christoph Hellwig authored
    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    this I need a so far unpublished patch from Andre, and it will be added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: default avatarChristoph Hellwig <hch@lst.de>
    Signed-off-by: default avatarArnd Bergmann <arnd.bergmann@de.ibm.com>
    2eb1b120
sched.c 12.7 KB