• Rafael J. Wysocki's avatar
    cpufreq: intel_pstate: Always set max P-state in performance mode · 2f1d407a
    Rafael J. Wysocki authored
    The only times at which intel_pstate checks the policy set for
    a given CPU is the initialization of that CPU and updates of its
    policy settings from cpufreq when intel_pstate_set_policy() is
    invoked.
    
    That is insufficient, however, because intel_pstate uses the same
    P-state selection function for all CPUs regardless of the policy
    setting for each of them and the P-state limits are shared between
    them.  Thus if the policy is set to "performance" for a particular
    CPU, it may not behave as expected if the cpufreq settings are
    changed subsequently for another CPU.
    
    That can be easily demonstrated by writing "performance" to
    scaling_governor for all CPUs and then switching it to "powersave"
    for one of them in which case all of the CPUs will behave as though
    their scaling_governor were all "powersave" (even though the policy
    still appears to be "performance" for the remaining CPUs).
    
    Fix this problem by modifying intel_pstate_adjust_busy_pstate() to
    always set the P-state to the maximum allowed by the current limits
    for all CPUs whose policy is set to "performance".
    
    Note that it still is recommended to always change the policy setting
    in the same way for all CPUs even with this fix applied to avoid
    confusion.
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    2f1d407a
intel_pstate.c 48.2 KB