[PATCH 2/2] sched/schedutil: rework iowait boost
From: Vincent Guittot
Date: Fri Oct 13 2023 - 11:15:09 EST
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@xxxxxxxxxx>
---
kernel/sched/cpufreq_schedutil.c | 29 ++++++++-------
kernel/sched/sched.h | 60 --------------------------------
2 files changed, 14 insertions(+), 75 deletions(-)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 8cb323522b90..820612867769 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c
@@ -177,11 +177,12 @@ unsigned long sugov_effective_cpu_perf(int cpu, unsigned long actual,
return max(target, 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 = map_util_perf(min);
sg_cpu->util = sugov_effective_cpu_perf(sg_cpu->cpu, util, min, max);
}
@@ -274,18 +275,16 @@ 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) {
/*
@@ -294,7 +293,7 @@ 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;
}
}
@@ -304,10 +303,7 @@ 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
@@ -337,6 +333,8 @@ 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;
@@ -345,8 +343,8 @@ 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;
}
@@ -447,9 +445,10 @@ 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 3873b4de7cfa..b181edaf4d41 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3026,59 +3026,6 @@ 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)
{
@@ -3116,13 +3063,6 @@ 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)
--
2.34.1