[3/4] cpufreq: intel_pstate: Add ->offline and ->online callbacks
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Message ID 1879185.C8Vd3vmt8n@kreacher
State New, archived
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Series
  • Untitled series #458960
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Commit Message

Rafael J. Wysocki Aug. 20, 2020, 4:38 p.m. UTC
From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>

Add ->offline and ->online driver callbacksto to do the cleanup
before taking a CPU offline and to restore its working configuration
when it goes back online, respectively, to avoid invoking the ->init
callback on every CPU online which is quite a bit of unnecessary
overhead.

Define ->offline and ->online so that they can be used in the
passive as well as in the active mode and because ->offline will
do the majority of ->stop_cpu work, the passive mode does not
need that callback any more, so drop it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 drivers/cpufreq/intel_pstate.c | 38 ++++++++++++++++++++++++++++------
 1 file changed, 32 insertions(+), 6 deletions(-)

Comments

Doug Smythies Aug. 22, 2020, 12:47 a.m. UTC | #1
Hi Rafael,

Just annoying typo type feedback.

On 2020.08.20 09:38 Rafael J. Wysocki wrote:

> 
> From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> 
> Add ->offline and ->online driver callbacksto to do the cleanup

"to to" and suggest this:

Add ->offline and ->online driver callbacks to cleanup

> before taking a CPU offline and to restore its working configuration
> when it goes back online, respectively, to avoid invoking the ->init
> callback on every CPU online which is quite a bit of unnecessary
> overhead.
> 
> Define ->offline and ->online so that they can be used in the
> passive as well as in the active mode and because ->offline will

  passive mode

> do the majority of ->stop_cpu work, the passive mode does not
> need that callback any more, so drop it.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> ---
>  drivers/cpufreq/intel_pstate.c | 38 ++++++++++++++++++++++++++++------
>  1 file changed, 32 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> index 3d18934fa975..aca0587b176f 100644
> --- a/drivers/cpufreq/intel_pstate.c
> +++ b/drivers/cpufreq/intel_pstate.c
> @@ -2297,28 +2297,51 @@ static int intel_pstate_verify_policy(struct cpufreq_policy_data *policy)
>  	return 0;
>  }
> 
> -static void intel_cpufreq_stop_cpu(struct cpufreq_policy *policy)
> +static int intel_pstate_cpu_offline(struct cpufreq_policy *policy)
>  {
> +	pr_debug("CPU %d going offline\n", policy->cpu);
> +
> +	intel_pstate_exit_perf_limits(policy);
> +
> +	/*
> +	 * If the CPU is an SMT thread and it goes offline with the performance
> +	 * settings different from the minimum, it will prevent its sibling
> +	 * from getting to lower performance levels, so force the minimum
> +	 * performance on CPU offline to prevent that form happening.

form/from

> +	 */
>  	if (hwp_active)
>  		intel_pstate_hwp_force_min_perf(policy->cpu);
>  	else
>  		intel_pstate_set_min_pstate(all_cpu_data[policy->cpu]);
> +
> +	return 0;
> +}
> +
> +static int intel_pstate_cpu_online(struct cpufreq_policy *policy)
> +{
> +	pr_debug("CPU %d going online\n", policy->cpu);
> +
> +	intel_pstate_init_acpi_perf_limits(policy);
> +
> +	if (hwp_active)
> +		wrmsrl_on_cpu(policy->cpu, MSR_HWP_REQUEST,
> +			      all_cpu_data[policy->cpu]->hwp_req_cached);
> +
> +	return 0;
>  }
> 
>  static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
>  {
> -	pr_debug("CPU %d exiting\n", policy->cpu);
> +	pr_debug("CPU %d stopping\n", policy->cpu);
> 
>  	intel_pstate_clear_update_util_hook(policy->cpu);
>  	if (hwp_active)
>  		intel_pstate_hwp_save_state(policy);
> -
> -	intel_cpufreq_stop_cpu(policy);
>  }
> 
>  static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
>  {
> -	intel_pstate_exit_perf_limits(policy);
> +	pr_debug("CPU %d exiting\n", policy->cpu);
> 
>  	policy->fast_switch_possible = false;
> 
> @@ -2398,6 +2421,8 @@ static struct cpufreq_driver intel_pstate = {
>  	.init		= intel_pstate_cpu_init,
>  	.exit		= intel_pstate_cpu_exit,
>  	.stop_cpu	= intel_pstate_stop_cpu,
> +	.offline	= intel_pstate_cpu_offline,
> +	.online		= intel_pstate_cpu_online,
>  	.update_limits	= intel_pstate_update_limits,
>  	.name		= "intel_pstate",
>  };
> @@ -2652,7 +2677,8 @@ static struct cpufreq_driver intel_cpufreq = {
>  	.fast_switch	= intel_cpufreq_fast_switch,
>  	.init		= intel_cpufreq_cpu_init,
>  	.exit		= intel_cpufreq_cpu_exit,
> -	.stop_cpu	= intel_cpufreq_stop_cpu,
> +	.offline	= intel_pstate_cpu_offline,
> +	.online		= intel_pstate_cpu_online,
>  	.update_limits	= intel_pstate_update_limits,
>  	.name		= "intel_cpufreq",
>  };
> --
> 2.26.2
> 
>

Patch
diff mbox series

diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 3d18934fa975..aca0587b176f 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -2297,28 +2297,51 @@  static int intel_pstate_verify_policy(struct cpufreq_policy_data *policy)
 	return 0;
 }
 
-static void intel_cpufreq_stop_cpu(struct cpufreq_policy *policy)
+static int intel_pstate_cpu_offline(struct cpufreq_policy *policy)
 {
+	pr_debug("CPU %d going offline\n", policy->cpu);
+
+	intel_pstate_exit_perf_limits(policy);
+
+	/*
+	 * If the CPU is an SMT thread and it goes offline with the performance
+	 * settings different from the minimum, it will prevent its sibling
+	 * from getting to lower performance levels, so force the minimum
+	 * performance on CPU offline to prevent that form happening.
+	 */
 	if (hwp_active)
 		intel_pstate_hwp_force_min_perf(policy->cpu);
 	else
 		intel_pstate_set_min_pstate(all_cpu_data[policy->cpu]);
+
+	return 0;
+}
+
+static int intel_pstate_cpu_online(struct cpufreq_policy *policy)
+{
+	pr_debug("CPU %d going online\n", policy->cpu);
+
+	intel_pstate_init_acpi_perf_limits(policy);
+
+	if (hwp_active)
+		wrmsrl_on_cpu(policy->cpu, MSR_HWP_REQUEST,
+			      all_cpu_data[policy->cpu]->hwp_req_cached);
+
+	return 0;
 }
 
 static void intel_pstate_stop_cpu(struct cpufreq_policy *policy)
 {
-	pr_debug("CPU %d exiting\n", policy->cpu);
+	pr_debug("CPU %d stopping\n", policy->cpu);
 
 	intel_pstate_clear_update_util_hook(policy->cpu);
 	if (hwp_active)
 		intel_pstate_hwp_save_state(policy);
-
-	intel_cpufreq_stop_cpu(policy);
 }
 
 static int intel_pstate_cpu_exit(struct cpufreq_policy *policy)
 {
-	intel_pstate_exit_perf_limits(policy);
+	pr_debug("CPU %d exiting\n", policy->cpu);
 
 	policy->fast_switch_possible = false;
 
@@ -2398,6 +2421,8 @@  static struct cpufreq_driver intel_pstate = {
 	.init		= intel_pstate_cpu_init,
 	.exit		= intel_pstate_cpu_exit,
 	.stop_cpu	= intel_pstate_stop_cpu,
+	.offline	= intel_pstate_cpu_offline,
+	.online		= intel_pstate_cpu_online,
 	.update_limits	= intel_pstate_update_limits,
 	.name		= "intel_pstate",
 };
@@ -2652,7 +2677,8 @@  static struct cpufreq_driver intel_cpufreq = {
 	.fast_switch	= intel_cpufreq_fast_switch,
 	.init		= intel_cpufreq_cpu_init,
 	.exit		= intel_cpufreq_cpu_exit,
-	.stop_cpu	= intel_cpufreq_stop_cpu,
+	.offline	= intel_pstate_cpu_offline,
+	.online		= intel_pstate_cpu_online,
 	.update_limits	= intel_pstate_update_limits,
 	.name		= "intel_cpufreq",
 };