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  • Peter Zijlstra's avatar
    sched: high-res preemption tick · 8f4d37ec
    Peter Zijlstra authored
    
    
    Use HR-timers (when available) to deliver an accurate preemption tick.
    
    The regular scheduler tick that runs at 1/HZ can be too coarse when nice
    level are used. The fairness system will still keep the cpu utilisation 'fair'
    by then delaying the task that got an excessive amount of CPU time but try to
    minimize this by delivering preemption points spot-on.
    
    The average frequency of this extra interrupt is sched_latency / nr_latency.
    Which need not be higher than 1/HZ, its just that the distribution within the
    sched_latency period is important.
    
    Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    8f4d37ec