• Ingo Molnar's avatar
    sched clock: revert various sched_clock() changes · e4e4e534
    Ingo Molnar authored
    Found an interactivity problem on a quad core test-system - simple
    CPU loops would occasionally delay the system un an unacceptable way.
    
    After much debugging with Peter Zijlstra it turned out that the problem
    is caused by the string of sched_clock() changes - they caused the CPU
    clock to jump backwards a bit - which confuses the scheduler arithmetics.
    
    (which is unsigned for performance reasons)
    
    So revert:
    
     # c300ba25: sched_clock: and multiplier for TSC to gtod drift
     # c0c87734: sched_clock: only update deltas with local reads.
     # af52a90a: sched_clock: stop maximum check on NO HZ
     # f7cce27f: sched_clock: widen the max and min time
    
    This solves the interactivity problems.
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
    Acked-by: default avatarMike Galbraith <efault@gmx.de>
    e4e4e534
tick-sched.c 17.2 KB