Message-ID: <CAJZ5v0ixj+9kJmXUtAdE4xdDHBEUg-KU_W=jKJbOEtUbq=OEGA@mail.gmail.com>
Date:   Thu, 9 Feb 2023 21:02:51 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
Cc:     rafael@...nel.org, rui.zhang@...el.com, daniel.lezcano@...aro.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [UPDATE][PATCH v3 2/2] thermal/drivers/intel_powerclamp: Add two
 module parameters

On Tue, Feb 7, 2023 at 6:35 PM Srinivas Pandruvada
<srinivas.pandruvada@...ux.intel.com> wrote:
>
> In some use cases, it is desirable to only inject idle on certain set
> of CPUs. For example on Alder Lake systems, it is possible that we force
> idle only on P-Cores for thermal reasons. Also the idle percent can be
> more than 50% if we only choose partial set of CPUs in the system.
>
> Introduce 2 new module parameters for this purpose. They can be only
> changed when the cooling device is inactive.
>
> cpumask (Read/Write): A bit mask of CPUs to inject idle. The format of
> this bitmask is same as used in other subsystems like in
> /proc/irq/*/smp_affinity. The mask is comma separated 32 bit groups.
> Each CPU is one bit. For example for 256 CPU system the full mask is:
> ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff
> The rightmost mask is for CPU 0-32.
>
> max_idle (Read/Write): Maximum injected idle time to the total CPU time
> ratio in percent range from 1 to 100. Even if the cooling device max_state
> is always 100 (100%), this parameter allows to add a max idle percent
> limit. The default is 50, to match the current implementation of powerclamp
> driver. Also doesn't allow value more than 75, if the cpumask includes
> every CPU present in the system.
>
> Also when the cpumask doesn't include every CPU, there is no use of
> compensation using package C-state idle counters. Hence don't start
> package C-state polling thread even for a single package or a single die
> system in this case.
>
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>
> ---
> v3 update:
> change leftmost to rightmost in commit description
>
> v3:
> One word document change from leftmost to rightmost
>
> v2:
> Addressed comments from v5 series from Rafael
> Build issue reported by Rui
>
>  .../admin-guide/thermal/intel_powerclamp.rst  |  22 +++
>  drivers/thermal/intel/intel_powerclamp.c      | 177 +++++++++++++++---
>  2 files changed, 178 insertions(+), 21 deletions(-)
>
> diff --git a/Documentation/admin-guide/thermal/intel_powerclamp.rst b/Documentation/admin-guide/thermal/intel_powerclamp.rst
> index 3f6dfb0b3ea6..2d9d2d739f02 100644
> --- a/Documentation/admin-guide/thermal/intel_powerclamp.rst
> +++ b/Documentation/admin-guide/thermal/intel_powerclamp.rst
> @@ -26,6 +26,8 @@ By:
>             - Generic Thermal Layer (sysfs)
>             - Kernel APIs (TBD)
>
> +       (*) Module Parameters
> +
>  INTRODUCTION
>  ============
>
> @@ -318,3 +320,23 @@ device, a PID based userspace thermal controller can manage to
>  control CPU temperature effectively, when no other thermal influence
>  is added. For example, a UltraBook user can compile the kernel under
>  certain temperature (below most active trip points).
> +
> +Module Parameters
> +=================
> +
> +``cpumask`` (RW)
> +       A bit mask of CPUs to inject idle. The format of the bitmask is same as
> +       used in other subsystems like in /proc/irq/*/smp_affinity. The mask is
> +       comma separated 32 bit groups. Each CPU is one bit. For example for a 256
> +       CPU system the full mask is:
> +       ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff,ffffffff
> +
> +       The rightmost mask is for CPU 0-32.
> +
> +``max_idle`` (RW)
> +       Maximum injected idle time to the total CPU time ratio in percent range
> +       from 1 to 100. Even if the cooling device max_state is always 100 (100%),
> +       this parameter allows to add a max idle percent limit. The default is 50,
> +       to match the current implementation of powerclamp driver. Also doesn't
> +       allow value more than 75, if the cpumask includes every CPU present in
> +       the system.
> diff --git a/drivers/thermal/intel/intel_powerclamp.c b/drivers/thermal/intel/intel_powerclamp.c
> index 1390748706a6..6d00ac597b8a 100644
> --- a/drivers/thermal/intel/intel_powerclamp.c
> +++ b/drivers/thermal/intel/intel_powerclamp.c
> @@ -37,7 +37,7 @@
>  #include <asm/mwait.h>
>  #include <asm/cpu_device_id.h>
>
> -#define MAX_TARGET_RATIO (50U)
> +#define MAX_TARGET_RATIO (100U)
>  /* For each undisturbed clamping period (no extra wake ups during idle time),
>   * we increment the confidence counter for the given target ratio.
>   * CONFIDENCE_OK defines the level where runtime calibration results are
> @@ -105,10 +105,144 @@ static const struct kernel_param_ops duration_ops = {
>         .get = param_get_int,
>  };
>
> -
>  module_param_cb(duration, &duration_ops, &duration, 0644);
>  MODULE_PARM_DESC(duration, "forced idle time for each attempt in msec.");
>
> +#define DEFAULT_MAX_IDLE       50
> +#define MAX_ALL_CPU_IDLE       75
> +
> +static u8 max_idle = DEFAULT_MAX_IDLE;
> +
> +static cpumask_var_t idle_injection_cpu_mask;
> +
> +static int allocate_copy_idle_injection_mask(const struct cpumask *copy_mask)
> +{
> +       if (cpumask_available(idle_injection_cpu_mask))
> +               goto copy_mask;
> +
> +       /* This mask is allocated only one time and freed during module exit */
> +       if (!alloc_cpumask_var(&idle_injection_cpu_mask, GFP_KERNEL))
> +               return -ENOMEM;
> +
> +copy_mask:
> +       cpumask_copy(idle_injection_cpu_mask, copy_mask);
> +
> +       return 0;
> +}
> +
> +/* Return true if the cpumask and idle percent combination is invalid */
> +static bool check_invalid(cpumask_var_t mask, u8 idle)
> +{
> +       if (cpumask_equal(cpu_present_mask, mask) && idle > MAX_ALL_CPU_IDLE)
> +               return true;
> +
> +       return false;
> +}
> +
> +static int cpumask_set(const char *arg, const struct kernel_param *kp)
> +{
> +       cpumask_var_t new_mask;
> +       int ret;
> +
> +       mutex_lock(&powerclamp_lock);
> +
> +       /* Can't set mask when cooling device is in use */
> +       if (powerclamp_data.clamping) {
> +               ret = -EAGAIN;
> +               goto skip_cpumask_set;
> +       }
> +
> +       ret = alloc_cpumask_var(&new_mask, GFP_KERNEL);
> +       if (!ret)
> +               goto skip_cpumask_set;
> +
> +       ret = bitmap_parse(arg, strlen(arg), cpumask_bits(new_mask),
> +                          nr_cpumask_bits);
> +       if (ret)
> +               goto free_cpumask_set;
> +
> +       if (cpumask_empty(new_mask) || check_invalid(new_mask, max_idle)) {
> +               ret = -EINVAL;
> +               goto free_cpumask_set;
> +       }
> +
> +       /*
> +        * When module parameters are passed from kernel command line
> +        * during insmod, the module parameter callback is called
> +        * before powerclamp_init(), so we can't assume that some
> +        * cpumask can be allocated and copied before here. Also
> +        * in this case this cpumask is used as the default mask.
> +        */
> +       ret = allocate_copy_idle_injection_mask(new_mask);
> +
> +free_cpumask_set:
> +       free_cpumask_var(new_mask);
> +skip_cpumask_set:
> +       mutex_unlock(&powerclamp_lock);
> +
> +       return ret;
> +}
> +
> +static int cpumask_get(char *buf, const struct kernel_param *kp)
> +{
> +       if (!cpumask_available(idle_injection_cpu_mask))
> +               return -ENODEV;
> +
> +       return bitmap_print_to_pagebuf(false, buf, cpumask_bits(idle_injection_cpu_mask),
> +                                      nr_cpumask_bits);
> +}
> +
> +static const struct kernel_param_ops cpumask_ops = {
> +       .set = cpumask_set,
> +       .get = cpumask_get,
> +};
> +
> +module_param_cb(cpumask, &cpumask_ops, NULL, 0644);
> +MODULE_PARM_DESC(cpumask, "Mask of CPUs to use for idle injection.");
> +
> +static int max_idle_set(const char *arg, const struct kernel_param *kp)
> +{
> +       u8 new_max_idle;
> +       int ret = 0;
> +
> +       mutex_lock(&powerclamp_lock);
> +
> +       /* Can't set mask when cooling device is in use */
> +       if (powerclamp_data.clamping) {
> +               ret = -EAGAIN;
> +               goto skip_limit_set;
> +       }
> +
> +       ret = kstrtou8(arg, 10, &new_max_idle);
> +       if (ret)
> +               goto skip_limit_set;
> +
> +       if (new_max_idle > MAX_TARGET_RATIO) {
> +               ret = -EINVAL;
> +               goto skip_limit_set;
> +       }
> +
> +       if (check_invalid(idle_injection_cpu_mask, new_max_idle)) {
> +               ret = -EINVAL;
> +               goto skip_limit_set;
> +       }
> +
> +       max_idle = new_max_idle;
> +
> +skip_limit_set:
> +       mutex_unlock(&powerclamp_lock);
> +
> +       return ret;
> +}
> +
> +static const struct kernel_param_ops max_idle_ops = {
> +       .set = max_idle_set,
> +       .get = param_get_int,
> +};
> +
> +module_param_cb(max_idle, &max_idle_ops, &max_idle, 0644);
> +MODULE_PARM_DESC(max_idle, "maximum injected idle time to the total CPU time ratio in percent range:1-100");
> +
>  struct powerclamp_calibration_data {
>         unsigned long confidence;  /* used for calibration, basically a counter
>                                     * gets incremented each time a clamping
> @@ -460,21 +594,15 @@ static void trigger_idle_injection(void)
>   */
>  static int powerclamp_idle_injection_register(void)
>  {
> -       /*
> -        * The idle inject core will only inject for online CPUs,
> -        * So we can register for all present CPUs. In this way
> -        * if some CPU goes online/offline while idle inject
> -        * is registered, nothing additional calls are required.
> -        * The same runtime and idle time is applicable for
> -        * newly onlined CPUs if any.
> -        *
> -        * Here cpu_present_mask can be used as is.
> -        * cast to (struct cpumask *) is required as the
> -        * cpu_present_mask is const struct cpumask *, otherwise
> -        * there will be compiler warnings.
> -        */
> -       ii_dev = idle_inject_register_full((struct cpumask *)cpu_present_mask,
> -                                          idle_inject_update);
> +       poll_pkg_cstate_enable = false;
> +       if (cpumask_equal(cpu_present_mask, idle_injection_cpu_mask)) {
> +               ii_dev = idle_inject_register_full(idle_injection_cpu_mask, idle_inject_update);
> +               if (topology_max_packages() == 1 && topology_max_die_per_package() == 1)
> +                       poll_pkg_cstate_enable = true;
> +       } else {
> +               ii_dev = idle_inject_register(idle_injection_cpu_mask);
> +       }
> +
>         if (!ii_dev) {
>                 pr_err("powerclamp: idle_inject_register failed\n");
>                 return -EAGAIN;
> @@ -555,7 +683,7 @@ static int powerclamp_set_cur_state(struct thermal_cooling_device *cdev,
>         mutex_lock(&powerclamp_lock);
>
>         new_target_ratio = clamp(new_target_ratio, 0UL,
> -                               (unsigned long) (MAX_TARGET_RATIO - 1));
> +                               (unsigned long) (max_idle - 1));
>         if (!powerclamp_data.target_ratio && new_target_ratio > 0) {
>                 pr_info("Start idle injection to reduce power\n");
>                 powerclamp_data.target_ratio = new_target_ratio;
> @@ -646,15 +774,19 @@ static int __init powerclamp_init(void)
>
>         /* probe cpu features and ids here */
>         retval = powerclamp_probe();
> +       if (retval)
> +               return retval;
> +
> +       mutex_lock(&powerclamp_lock);
> +       retval = allocate_copy_idle_injection_mask(cpu_present_mask);
> +       mutex_unlock(&powerclamp_lock);
> +
>         if (retval)
>                 return retval;
>
>         /* set default limit, maybe adjusted during runtime based on feedback */
>         window_size = 2;
>
> -       if (topology_max_packages() == 1 && topology_max_die_per_package() == 1)
> -               poll_pkg_cstate_enable = true;
> -
>         cooling_dev = thermal_cooling_device_register("intel_powerclamp", NULL,
>                                                       &powerclamp_cooling_ops);
>         if (IS_ERR(cooling_dev))
> @@ -679,6 +811,9 @@ static void __exit powerclamp_exit(void)
>
>         cancel_delayed_work_sync(&poll_pkg_cstate_work);
>         debugfs_remove_recursive(debug_dir);
> +
> +       if (cpumask_available(idle_injection_cpu_mask))
> +               free_cpumask_var(idle_injection_cpu_mask);
>  }
>  module_exit(powerclamp_exit);
>
> --

Applied as 6.3 material along with the [1/2], thanks!

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