Currently in intel_pstate_clear_update_util_hook, after clearing the utilization update hook, we leverage synchronize_sched() to deal with synchronization, which is a little bit time-costly because synchronize_sched() has to wait for all the CPUs to go through a grace period.
Actually, the synchronize_sched() is not necessary if the utilization update hook has not been set for the given CPU yet, so make the driver check if that's the case and avoid the synchronize_sched() call in that case. Link: https://bugzilla.kernel.org/show_bug.cgi?id=116371 Tested-by: Tian Ye <yex.t...@intel.com> Signed-off-by: Chen Yu <yu.c.c...@intel.com> --- v2: - Rewrite the commit log according to Rafael's suggestion. --- drivers/cpufreq/intel_pstate.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c index b230eba..9811e4e 100644 --- a/drivers/cpufreq/intel_pstate.c +++ b/drivers/cpufreq/intel_pstate.c @@ -162,6 +162,7 @@ struct _pid { * struct cpudata - Per CPU instance data storage * @cpu: CPU number for this instance data * @update_util: CPUFreq utility callback information + * @update_util_set: CPUFreq utility callback is set * @pstate: Stores P state limits for this CPU * @vid: Stores VID limits for this CPU * @pid: Stores PID parameters for this CPU @@ -179,6 +180,7 @@ struct cpudata { int cpu; struct update_util_data update_util; + bool update_util_set; struct pstate_data pstate; struct vid_data vid; @@ -1287,11 +1289,18 @@ static void intel_pstate_set_update_util_hook(unsigned int cpu_num) /* Prevent intel_pstate_update_util() from using stale data. */ cpu->sample.time = 0; cpufreq_set_update_util_data(cpu_num, &cpu->update_util); + cpu->update_util_set = true; } static void intel_pstate_clear_update_util_hook(unsigned int cpu) { + struct cpudata *cpu_data = all_cpu_data[cpu]; + + if (!cpu_data->update_util_set) + return; + cpufreq_set_update_util_data(cpu, NULL); + cpu_data->update_util_set = false; synchronize_sched(); } -- 2.7.4
