• Paul Turner's avatar
    sched: Prevent interactions with throttled entities · 64660c86
    Paul Turner authored
    From the perspective of load-balance and shares distribution, throttled
    entities should be invisible.
    
    However, both of these operations work on 'active' lists and are not
    inherently aware of what group hierarchies may be present.  In some cases this
    may be side-stepped (e.g. we could sideload via tg_load_down in load balance)
    while in others (e.g. update_shares()) it is more difficult to compute without
    incurring some O(n^2) costs.
    
    Instead, track hierarchicaal throttled state at time of transition.  This
    allows us to easily identify whether an entity belongs to a throttled hierarchy
    and avoid incorrect interactions with it.
    
    Also, when an entity leaves a throttled hierarchy we need to advance its
    time averaging for shares averaging so that the elapsed throttled time is not
    considered as part of the cfs_rq's operation.
    
    We also use this information to prevent buddy interactions in the wakeup and
    yield_to() paths.
    Signed-off-by: default avatarPaul Turner <pjt@google.com>
    Reviewed-by: default avatarHidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
    Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/20110721184757.777916795@google.comSigned-off-by: default avatarIngo Molnar <mingo@elte.hu>
    64660c86
sched.c 232 KB