intel_pstate: skip scheduler hook when in "performance" mode

When the governor is set to "performance", intel_pstate does not
need the scheduler hook for doing any calculations.  Under these
conditions, its only purpose is to continue to maintain
cpufreq/scaling_cur_freq.

The cpufreq/scaling_cur_freq sysfs attribute is now provided by
shared x86 cpufreq code on modern x86 systems, including
all systems supported by the intel_pstate driver.

So in "performance" governor mode, the scheduler hook can be skipped.
This applies to both in Software and Hardware P-state control modes.

Suggested-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index b00a455..1772d30 100644 (file)
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2044,10 +2044,10 @@ static int intel_pstate_set_policy(struct cpufreq_policy *policy)
                 */
                intel_pstate_clear_update_util_hook(policy->cpu);
                intel_pstate_max_within_limits(cpu);
+       } else {
+               intel_pstate_set_update_util_hook(policy->cpu);
        }
 
-       intel_pstate_set_update_util_hook(policy->cpu);
-
        if (hwp_active)
                intel_pstate_hwp_set(policy->cpu);