sched/cpufreq: Rework iowait boost

Use the max value that has already been computed inside sugov_get_util()
to cap the iowait boost and remove dependency with uclamp_rq_util_with()
which is not used anymore.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20231122133904.446032-3-vincent.guittot@linaro.org

diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index f3acf2cf26ed6c0a68049553e67dc8d59e99c157..4ee8ad70be9974dfc9efed19ef93640543f9b968 100644 (file)
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -169,11 +169,12 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
        return max(min, max);
 }
 
-static void sugov_get_util(struct sugov_cpu *sg_cpu)
+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);
 }
@@ -266,18 +267,16 @@ 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 void sugov_iowait_apply(struct sugov_cpu *sg_cpu, u64 time,
+static unsigned long 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;
+               return 0;
 
        /* Reset boost if the CPU appears to have been idle enough */
        if (sugov_iowait_reset(sg_cpu, time, false))
-               return;
+               return 0;
 
        if (!sg_cpu->iowait_boost_pending) {
                /*
@@ -286,7 +285,7 @@ static void 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;
+                       return 0;
                }
        }
 
@@ -296,10 +295,7 @@ static void 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.
         */
-       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;
+       return (sg_cpu->iowait_boost * max_cap) >> SCHED_CAPACITY_SHIFT;
 }
 
 #ifdef CONFIG_NO_HZ_COMMON
@@ -329,6 +325,8 @@ 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;
 
@@ -337,8 +335,8 @@ static inline bool sugov_update_single_common(struct sugov_cpu *sg_cpu,
        if (!sugov_should_update_freq(sg_cpu->sg_policy, time))
                return false;
 
-       sugov_get_util(sg_cpu);
-       sugov_iowait_apply(sg_cpu, time, max_cap);
+       boost = sugov_iowait_apply(sg_cpu, time, max_cap);
+       sugov_get_util(sg_cpu, boost);
 
        return true;
 }
@@ -439,9 +437,10 @@ 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;
 
-               sugov_get_util(j_sg_cpu);
-               sugov_iowait_apply(j_sg_cpu, time, max_cap);
+               boost = sugov_iowait_apply(j_sg_cpu, time, max_cap);
+               sugov_get_util(j_sg_cpu, boost);
 
                util = max(j_sg_cpu->util, util);
        }

diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index c1574cd388e73a2ebf51067f298c4db014603410..e58a54bda77def14f0823cad01137652d7d201b6 100644 (file)
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3058,59 +3058,6 @@ 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)
 {
@@ -3148,13 +3095,6 @@ 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)