Re: [PATCH] Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commit

[Vincent Guittot <vincent.guittot@linaro.org>]

On Thu, 11 Jan 2024 at 21:48, Ingo Molnar <mingo@kernel.org> wrote:
>
>
> * Vincent Guittot <vincent.guittot@linaro.org> wrote:
>
> > On Thu, 11 Jan 2024 at 12:09, Ingo Molnar <mingo@kernel.org> wrote:
> > >
> > >
> > > * Linus Torvalds <torvalds@linux-foundation.org> wrote:
> > >
> > > > On Wed, 10 Jan 2024 at 14:41, Linus Torvalds
> > > > <torvalds@linux-foundation.org> wrote:
> > > > >
> > > > > It's one of these two:
> > > > >
> > > > >   f12560779f9d sched/cpufreq: Rework iowait boost
> > > > >   9c0b4bb7f630 sched/cpufreq: Rework schedutil governor performance estimation
> > > > >
> > > > > one more boot to go, then I'll try to revert whichever causes my
> > > > > machine to perform horribly much worse.
> > > >
> > > > I guess it should come as no surprise that the result is
> > > >
> > > >    9c0b4bb7f6303c9c4e2e34984c46f5a86478f84d is the first bad commit
> > > >
> > > > but to revert cleanly I will have to revert all of
> > > >
> > > >       b3edde44e5d4 ("cpufreq/schedutil: Use a fixed reference frequency")
> > > >       f12560779f9d ("sched/cpufreq: Rework iowait boost")
> > > >       9c0b4bb7f630 ("sched/cpufreq: Rework schedutil governor
> > > > performance estimation")
> > > >
> > > > This is on a 32-core (64-thread) AMD Ryzen Threadripper 3970X, fwiw.
> > > >
> > > > I'll keep that revert in my private test-tree for now (so that I have
> > > > a working machine again), but I'll move it to my main branch soon
> > > > unless somebody has a quick fix for this problem.
> > >
> > > Thanks a lot for bisecting this, and ack on the revert in any case, these
> > > are relatively fresh changes that clearly didn't get enough testing - sorry!
> >
> > b3edde44e5d4 ("cpufreq/schedutil: Use a fixed reference frequency") is
> > linked with other patches.
>
> Indeed.
>
> > I can provide a clean revert of only :
> > f12560779f9d ("sched/cpufreq: Rework iowait boost")
> > 9c0b4bb7f630 ("sched/cpufreq: Rework schedutil governor performance estimation")
>
> I've done this too, see this new commit in sched/urgent:
>
>   60ee1706bd11 ("Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commit")

Thanks, your new commit looks good to me.

>
> Also attached below.
>
> > if the fix that i proposed doesn't work:
> > https://lore.kernel.org/all/ZZ+ixagkxRPYyTCE@vingu-book/
>
> Yeah - although of course Linus is free to just pull the revert as well.

Yes, I know

> I'll try to reproduce the regression locally as well.

Ok, Thanks

Vincent

>
> Thanks,
>
>         Ingo
>
> ===============================>
> From: Ingo Molnar <mingo@kernel.org>
> Date: Thu, 11 Jan 2024 11:45:17 +0100
> Subject: [PATCH] Revert "sched/cpufreq: Rework schedutil governor performance estimation" and dependent commit
>
> This reverts the following commits:
>
>   f12560779f9d73 ("sched/cpufreq: Rework iowait boost")
>   9c0b4bb7f6303c ("sched/cpufreq: Rework schedutil governor performance estimation")
>
> Because Linus reported a bad performance regression with the
> sched_util governor, that increased the time his empty
> kernel build took from 22 to 44 seconds (and can be similarly
> measured in full builds as well) - and bisected it back to 9c0b4bb7f6303c.
>
> Until we have a proper fix, revert the broken commit and its
> dependent commit.
>
> Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> Bisected-by: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> Cc: Vincent Guittot <vincent.guittot@linaro.org>
> Link: https://lore.kernel.org/r/CAHk-=wgWcYX2oXKtgvNN2LLDXP7kXkbo-xTfumEjmPbjSer2RQ@mail.gmail.com
> ---
>  include/linux/energy_model.h     |  1 +
>  kernel/sched/core.c              | 90 +++++++++++++++++++++++-----------------
>  kernel/sched/cpufreq_schedutil.c | 64 +++++++++++-----------------
>  kernel/sched/fair.c              | 22 ++--------
>  kernel/sched/sched.h             | 84 +++++++++++++++++++++++++++++++++----
>  5 files changed, 158 insertions(+), 103 deletions(-)
>
> diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h
> index 88d91e087471..c19e7effe764 100644
> --- a/include/linux/energy_model.h
> +++ b/include/linux/energy_model.h
> @@ -243,6 +243,7 @@ static inline unsigned long em_cpu_energy(struct em_perf_domain *pd,
>         scale_cpu = arch_scale_cpu_capacity(cpu);
>         ref_freq = arch_scale_freq_ref(cpu);
>
> +       max_util = map_util_perf(max_util);
>         max_util = min(max_util, allowed_cpu_cap);
>         freq = map_util_freq(max_util, ref_freq, scale_cpu);
>
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 9116bcc90346..038eeaf76d2d 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -7468,13 +7468,18 @@ int sched_core_idle_cpu(int cpu)
>   * required to meet deadlines.
>   */
>  unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
> -                                unsigned long *min,
> -                                unsigned long *max)
> +                                enum cpu_util_type type,
> +                                struct task_struct *p)
>  {
> -       unsigned long util, irq, scale;
> +       unsigned long dl_util, util, irq, max;
>         struct rq *rq = cpu_rq(cpu);
>
> -       scale = arch_scale_cpu_capacity(cpu);
> +       max = arch_scale_cpu_capacity(cpu);
> +
> +       if (!uclamp_is_used() &&
> +           type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) {
> +               return max;
> +       }
>
>         /*
>          * Early check to see if IRQ/steal time saturates the CPU, can be
> @@ -7482,49 +7487,45 @@ unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
>          * update_irq_load_avg().
>          */
>         irq = cpu_util_irq(rq);
> -       if (unlikely(irq >= scale)) {
> -               if (min)
> -                       *min = scale;
> -               if (max)
> -                       *max = scale;
> -               return scale;
> -       }
> -
> -       if (min) {
> -               /*
> -                * The minimum utilization returns the highest level between:
> -                * - the computed DL bandwidth needed with the IRQ pressure which
> -                *   steals time to the deadline task.
> -                * - The minimum performance requirement for CFS and/or RT.
> -                */
> -               *min = max(irq + cpu_bw_dl(rq), uclamp_rq_get(rq, UCLAMP_MIN));
> -
> -               /*
> -                * When an RT task is runnable and uclamp is not used, we must
> -                * ensure that the task will run at maximum compute capacity.
> -                */
> -               if (!uclamp_is_used() && rt_rq_is_runnable(&rq->rt))
> -                       *min = max(*min, scale);
> -       }
> +       if (unlikely(irq >= max))
> +               return max;
>
>         /*
>          * Because the time spend on RT/DL tasks is visible as 'lost' time to
>          * CFS tasks and we use the same metric to track the effective
>          * utilization (PELT windows are synchronized) we can directly add them
>          * to obtain the CPU's actual utilization.
> +        *
> +        * CFS and RT utilization can be boosted or capped, depending on
> +        * utilization clamp constraints requested by currently RUNNABLE
> +        * tasks.
> +        * When there are no CFS RUNNABLE tasks, clamps are released and
> +        * frequency will be gracefully reduced with the utilization decay.
>          */
>         util = util_cfs + cpu_util_rt(rq);
> -       util += cpu_util_dl(rq);
> +       if (type == FREQUENCY_UTIL)
> +               util = uclamp_rq_util_with(rq, util, p);
> +
> +       dl_util = cpu_util_dl(rq);
>
>         /*
> -        * The maximum hint is a soft bandwidth requirement, which can be lower
> -        * than the actual utilization because of uclamp_max requirements.
> +        * For frequency selection we do not make cpu_util_dl() a permanent part
> +        * of this sum because we want to use cpu_bw_dl() later on, but we need
> +        * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such
> +        * that we select f_max when there is no idle time.
> +        *
> +        * NOTE: numerical errors or stop class might cause us to not quite hit
> +        * saturation when we should -- something for later.
>          */
> -       if (max)
> -               *max = min(scale, uclamp_rq_get(rq, UCLAMP_MAX));
> +       if (util + dl_util >= max)
> +               return max;
>
> -       if (util >= scale)
> -               return scale;
> +       /*
> +        * OTOH, for energy computation we need the estimated running time, so
> +        * include util_dl and ignore dl_bw.
> +        */
> +       if (type == ENERGY_UTIL)
> +               util += dl_util;
>
>         /*
>          * There is still idle time; further improve the number by using the
> @@ -7535,15 +7536,28 @@ unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
>          *   U' = irq + --------- * U
>          *                 max
>          */
> -       util = scale_irq_capacity(util, irq, scale);
> +       util = scale_irq_capacity(util, irq, max);
>         util += irq;
>
> -       return min(scale, util);
> +       /*
> +        * Bandwidth required by DEADLINE must always be granted while, for
> +        * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism
> +        * to gracefully reduce the frequency when no tasks show up for longer
> +        * periods of time.
> +        *
> +        * Ideally we would like to set bw_dl as min/guaranteed freq and util +
> +        * bw_dl as requested freq. However, cpufreq is not yet ready for such
> +        * an interface. So, we only do the latter for now.
> +        */
> +       if (type == FREQUENCY_UTIL)
> +               util += cpu_bw_dl(rq);
> +
> +       return min(max, util);
>  }
>
>  unsigned long sched_cpu_util(int cpu)
>  {
> -       return effective_cpu_util(cpu, cpu_util_cfs(cpu), NULL, NULL);
> +       return effective_cpu_util(cpu, cpu_util_cfs(cpu), ENERGY_UTIL, NULL);
>  }
>  #endif /* CONFIG_SMP */
>
> diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
> index 95c3c097083e..5f8729c41d0a 100644
> --- a/kernel/sched/cpufreq_schedutil.c
> +++ b/kernel/sched/cpufreq_schedutil.c
> @@ -47,7 +47,7 @@ struct sugov_cpu {
>         u64                     last_update;
>
>         unsigned long           util;
> -       unsigned long           bw_min;
> +       unsigned long           bw_dl;
>
>         /* The field below is for single-CPU policies only: */
>  #ifdef CONFIG_NO_HZ_COMMON
> @@ -164,6 +164,7 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
>         struct cpufreq_policy *policy = sg_policy->policy;
>         unsigned int freq;
>
> +       util = map_util_perf(util);
>         freq = get_capacity_ref_freq(policy);
>         freq = map_util_freq(util, freq, max);
>
> @@ -174,31 +175,14 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy,
>         return cpufreq_driver_resolve_freq(policy, freq);
>  }
>
> -unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
> -                                unsigned long min,
> -                                unsigned long max)
> +static void sugov_get_util(struct sugov_cpu *sg_cpu)
>  {
> -       /* Add dvfs headroom to actual utilization */
> -       actual = map_util_perf(actual);
> -       /* Actually we don't need to target the max performance */
> -       if (actual < max)
> -               max = actual;
> +       unsigned long util = cpu_util_cfs_boost(sg_cpu->cpu);
> +       struct rq *rq = cpu_rq(sg_cpu->cpu);
>
> -       /*
> -        * Ensure at least minimum performance while providing more compute
> -        * capacity when possible.
> -        */
> -       return max(min, max);
> -}
> -
> -static void sugov_get_util(struct sugov_cpu *sg_cpu, unsigned long boost)
> -{
> -       unsigned long min, max, util = cpu_util_cfs_boost(sg_cpu->cpu);
> -
> -       util = effective_cpu_util(sg_cpu->cpu, util, &min, &max);
> -       util = max(util, boost);
> -       sg_cpu->bw_min = min;
> -       sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max);
> +       sg_cpu->bw_dl = cpu_bw_dl(rq);
> +       sg_cpu->util = effective_cpu_util(sg_cpu->cpu, util,
> +                                         FREQUENCY_UTIL, NULL);
>  }
>
>  /**
> @@ -289,16 +273,18 @@ static void sugov_iowait_boost(struct sugov_cpu *sg_cpu, u64 time,
>   * This mechanism is designed to boost high frequently IO waiting tasks, while
>   * being more conservative on tasks which does sporadic IO operations.
>   */
> -static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
> +static void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
>                                unsigned long max_cap)
>  {
> +       unsigned long boost;
> +
>         /* No boost currently required */
>         if (!sg_cpu->iowait_boost)
> -               return 0;
> +               return;
>
>         /* Reset boost if the CPU appears to have been idle enough */
>         if (sugov_iowait_reset(sg_cpu, time, false))
> -               return 0;
> +               return;
>
>         if (!sg_cpu->iowait_boost_pending) {
>                 /*
> @@ -307,7 +293,7 @@ static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
>                 sg_cpu->iowait_boost >>= 1;
>                 if (sg_cpu->iowait_boost < IOWAIT_BOOST_MIN) {
>                         sg_cpu->iowait_boost = 0;
> -                       return 0;
> +                       return;
>                 }
>         }
>
> @@ -317,7 +303,10 @@ static unsigned long sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
>          * sg_cpu->util is already in capacity scale; convert iowait_boost
>          * into the same scale so we can compare.
>          */
> -       return (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT;
> +       boost = (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT;
> +       boost = uclamp_rq_util_with(cpu_rq(sg_cpu->cpu), boost, NULL);
> +       if (sg_cpu->util < boost)
> +               sg_cpu->util = boost;
>  }
>
>  #ifdef CONFIG_NO_HZ_COMMON
> @@ -339,7 +328,7 @@ static inline bool sugov_cpu_is_busy(struct sugov_cpu *sg_cpu) { return false; }
>   */
>  static inline void ignore_dl_rate_limit(struct sugov_cpu *sg_cpu)
>  {
> -       if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_min)
> +       if (cpu_bw_dl(cpu_rq(sg_cpu->cpu)) > sg_cpu->bw_dl)
>                 sg_cpu->sg_policy->limits_changed = true;
>  }
>
> @@ -347,8 +336,6 @@ static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
>                                               u64 time, unsigned long max_cap,
>                                               unsigned int flags)
>  {
> -       unsigned long boost;
> -
>         sugov_iowait_boost(sg_cpu, time, flags);
>         sg_cpu->last_update = time;
>
> @@ -357,8 +344,8 @@ static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
>         if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
>                 return false;
>
> -       boost = sugov_iowait_apply(sg_cpu, time, max_cap);
> -       sugov_get_util(sg_cpu, boost);
> +       sugov_get_util(sg_cpu);
> +       sugov_iowait_apply(sg_cpu, time, max_cap);
>
>         return true;
>  }
> @@ -442,8 +429,8 @@ static void sugov_update_single_perf(struct update_util_data *hook, u64 time,
>             sugov_cpu_is_busy(sg_cpu) && sg_cpu->util < prev_util)
>                 sg_cpu->util = prev_util;
>
> -       cpufreq_driver_adjust_perf(sg_cpu->cpu, sg_cpu->bw_min,
> -                                  sg_cpu->util, max_cap);
> +       cpufreq_driver_adjust_perf(sg_cpu->cpu, map_util_perf(sg_cpu->bw_dl),
> +                                  map_util_perf(sg_cpu->util), max_cap);
>
>         sg_cpu->sg_policy->last_freq_update_time = time;
>  }
> @@ -459,10 +446,9 @@ static unsigned int sugov_next_freq_shared(struct sugov_cpu *sg_cpu, u64 time)
>
>         for_each_cpu(j, policy->cpus) {
>                 struct sugov_cpu *j_sg_cpu = &per_cpu(sugov_cpu, j);
> -               unsigned long boost;
>
> -               boost = sugov_iowait_apply(j_sg_cpu, time, max_cap);
> -               sugov_get_util(j_sg_cpu, boost);
> +               sugov_get_util(j_sg_cpu);
> +               sugov_iowait_apply(j_sg_cpu, time, max_cap);
>
>                 util = max(j_sg_cpu->util, util);
>         }
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 533547e3c90a..f2bb83675e4a 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -7820,7 +7820,7 @@ static inline void eenv_pd_busy_time(struct energy_env *eenv,
>         for_each_cpu(cpu, pd_cpus) {
>                 unsigned long util = cpu_util(cpu, p, -1, 0);
>
> -               busy_time += effective_cpu_util(cpu, util, NULL, NULL);
> +               busy_time += effective_cpu_util(cpu, util, ENERGY_UTIL, NULL);
>         }
>
>         eenv->pd_busy_time = min(eenv->pd_cap, busy_time);
> @@ -7843,7 +7843,7 @@ eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
>         for_each_cpu(cpu, pd_cpus) {
>                 struct task_struct *tsk = (cpu == dst_cpu) ? p : NULL;
>                 unsigned long util = cpu_util(cpu, p, dst_cpu, 1);
> -               unsigned long eff_util, min, max;
> +               unsigned long eff_util;
>
>                 /*
>                  * Performance domain frequency: utilization clamping
> @@ -7852,23 +7852,7 @@ eenv_pd_max_util(struct energy_env *eenv, struct cpumask *pd_cpus,
>                  * NOTE: in case RT tasks are running, by default the
>                  * FREQUENCY_UTIL's utilization can be max OPP.
>                  */
> -               eff_util = effective_cpu_util(cpu, util, &min, &max);
> -
> -               /* Task's uclamp can modify min and max value */
> -               if (tsk && uclamp_is_used()) {
> -                       min = max(min, uclamp_eff_value(p, UCLAMP_MIN));
> -
> -                       /*
> -                        * If there is no active max uclamp constraint,
> -                        * directly use task's one, otherwise keep max.
> -                        */
> -                       if (uclamp_rq_is_idle(cpu_rq(cpu)))
> -                               max = uclamp_eff_value(p, UCLAMP_MAX);
> -                       else
> -                               max = max(max, uclamp_eff_value(p, UCLAMP_MAX));
> -               }
> -
> -               eff_util = sugov_effective_cpu_perf(cpu, eff_util, min, max);
> +               eff_util = effective_cpu_util(cpu, util, FREQUENCY_UTIL, tsk);
>                 max_util = max(max_util, eff_util);
>         }
>
> diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
> index 001fe047bd5d..eb7e07a1abcc 100644
> --- a/kernel/sched/sched.h
> +++ b/kernel/sched/sched.h
> @@ -3005,14 +3005,24 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
>  #endif
>
>  #ifdef CONFIG_SMP
> +/**
> + * enum cpu_util_type - CPU utilization type
> + * @FREQUENCY_UTIL:    Utilization used to select frequency
> + * @ENERGY_UTIL:       Utilization used during energy calculation
> + *
> + * The utilization signals of all scheduling classes (CFS/RT/DL) and IRQ time
> + * need to be aggregated differently depending on the usage made of them. This
> + * enum is used within effective_cpu_util() to differentiate the types of
> + * utilization expected by the callers, and adjust the aggregation accordingly.
> + */
> +enum cpu_util_type {
> +       FREQUENCY_UTIL,
> +       ENERGY_UTIL,
> +};
> +
>  unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
> -                                unsigned long *min,
> -                                unsigned long *max);
> -
> -unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
> -                                unsigned long min,
> -                                unsigned long max);
> -
> +                                enum cpu_util_type type,
> +                                struct task_struct *p);
>
>  /*
>   * Verify the fitness of task @p to run on @cpu taking into account the
> @@ -3069,6 +3079,59 @@ static inline bool uclamp_rq_is_idle(struct rq *rq)
>         return rq->uclamp_flags & UCLAMP_FLAG_IDLE;
>  }
>
> +/**
> + * uclamp_rq_util_with - clamp @util with @rq and @p effective uclamp values.
> + * @rq:                The rq to clamp against. Must not be NULL.
> + * @util:      The util value to clamp.
> + * @p:         The task to clamp against. Can be NULL if you want to clamp
> + *             against @rq only.
> + *
> + * Clamps the passed @util to the max(@rq, @p) effective uclamp values.
> + *
> + * If sched_uclamp_used static key is disabled, then just return the util
> + * without any clamping since uclamp aggregation at the rq level in the fast
> + * path is disabled, rendering this operation a NOP.
> + *
> + * Use uclamp_eff_value() if you don't care about uclamp values at rq level. It
> + * will return the correct effective uclamp value of the task even if the
> + * static key is disabled.
> + */
> +static __always_inline
> +unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
> +                                 struct task_struct *p)
> +{
> +       unsigned long min_util = 0;
> +       unsigned long max_util = 0;
> +
> +       if (!static_branch_likely(&sched_uclamp_used))
> +               return util;
> +
> +       if (p) {
> +               min_util = uclamp_eff_value(p, UCLAMP_MIN);
> +               max_util = uclamp_eff_value(p, UCLAMP_MAX);
> +
> +               /*
> +                * Ignore last runnable task's max clamp, as this task will
> +                * reset it. Similarly, no need to read the rq's min clamp.
> +                */
> +               if (uclamp_rq_is_idle(rq))
> +                       goto out;
> +       }
> +
> +       min_util = max_t(unsigned long, min_util, uclamp_rq_get(rq, UCLAMP_MIN));
> +       max_util = max_t(unsigned long, max_util, uclamp_rq_get(rq, UCLAMP_MAX));
> +out:
> +       /*
> +        * Since CPU's {min,max}_util clamps are MAX aggregated considering
> +        * RUNNABLE tasks with _different_ clamps, we can end up with an
> +        * inversion. Fix it now when the clamps are applied.
> +        */
> +       if (unlikely(min_util >= max_util))
> +               return min_util;
> +
> +       return clamp(util, min_util, max_util);
> +}
> +
>  /* Is the rq being capped/throttled by uclamp_max? */
>  static inline bool uclamp_rq_is_capped(struct rq *rq)
>  {
> @@ -3106,6 +3169,13 @@ static inline unsigned long uclamp_eff_value(struct task_struct *p,
>         return SCHED_CAPACITY_SCALE;
>  }
>
> +static inline
> +unsigned long uclamp_rq_util_with(struct rq *rq, unsigned long util,
> +                                 struct task_struct *p)
> +{
> +       return util;
> +}
> +
>  static inline bool uclamp_rq_is_capped(struct rq *rq) { return false; }
>
>  static inline bool uclamp_is_used(void)