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    cpuidle: menu: Fall back to polling if next timer event is near · 0c313cb2
    Rafael J. Wysocki 提交于
    Commit a9ceb78b (cpuidle,menu: use interactivity_req to disable
    polling) changed the behavior of the fallback state selection part
    of menu_select() so it looks at interactivity_req instead of
    data->next_timer_us when it makes its decision.  That effectively
    caused polling to be used more often as fallback idle which led to
    significant increases of energy consumption in some cases.
    
    Commit e132b9b3 (cpuidle: menu: use high confidence factors
    only when considering polling) changed that logic again to be more
    predictable, but that didn't help with the increased energy
    consumption problem.
    
    For this reason, go back to making decisions on which state to fall
    back to based on data->next_timer_us which is the time we know for
    sure something will happen rather than a prediction (which may be
    inaccurate and turns out to be so often enough to be problematic).
    However, take the target residency of the first proper idle state
    (C1) into account, so that state is not used as the fallback one
    if its target residency is greater than data->next_timer_us.
    
    Fixes: a9ceb78b (cpuidle,menu: use interactivity_req to disable polling)
    Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Reported-and-tested-by: NDoug Smythies <dsmythies@telus.net>
    0c313cb2
menu.c 15.2 KB