linux-pikaos-template/patches/0002-eevdfbore.patch

From 5e3bbb489086974a823af55f23cc17d2ea032f8b Mon Sep 17 00:00:00 2001
From: Piotr Gorski <lucjan.lucjanov@gmail.com>
Date: Sun, 18 Jun 2023 11:05:43 +0200
Subject: [PATCH] bore-eevdf

Signed-off-by: Piotr Gorski <lucjan.lucjanov@gmail.com>
---
 include/linux/sched.h   |  10 +++
 init/Kconfig            |  20 +++++
 kernel/sched/core.c     |  62 +++++++++++++
 kernel/sched/debug.c    |   4 +
 kernel/sched/fair.c     | 193 ++++++++++++++++++++++++++++++++++++++--
 kernel/sched/features.h |   4 +
 kernel/sched/sched.h    |   1 +
 7 files changed, 286 insertions(+), 8 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 63ac38d66..63a2205a5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -560,6 +560,12 @@ struct sched_entity {
 	u64				sum_exec_runtime;
 	u64				prev_sum_exec_runtime;
 	u64				vruntime;
+#ifdef CONFIG_SCHED_BORE
+	u64				prev_burst_time;
+	u64				burst_time;
+	u64				max_burst_time;
+	u8				penalty_score;
+#endif // CONFIG_SCHED_BORE
 	s64				vlag;
 	u64				slice;
 
@@ -991,6 +997,10 @@ struct task_struct {
 	struct list_head		children;
 	struct list_head		sibling;
 	struct task_struct		*group_leader;
+#ifdef CONFIG_SCHED_BORE
+	u64	child_burst_cache;
+	u64	child_burst_last_cached;
+#endif // CONFIG_SCHED_BORE
 
 	/*
 	 * 'ptraced' is the list of tasks this task is using ptrace() on.
diff --git a/init/Kconfig b/init/Kconfig
index 0147b4a33..4ab7e154b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1290,6 +1290,26 @@ config CHECKPOINT_RESTORE
 
 	  If unsure, say N here.
 
+config SCHED_BORE
+	bool "Burst-Oriented Response Enhancer"
+	default y
+	help
+	  In Desktop and Mobile computing, one might prefer interactive
+	  tasks to keep responsive no matter what they run in the background.
+
+	  Enabling this kernel feature modifies the scheduler to discriminate
+	  tasks by their burst time (runtime since it last went sleeping or
+	  yielding state) and prioritize those that run less bursty.
+	  Such tasks usually include window compositor, widgets backend,
+	  terminal emulator, video playback, games and so on.
+	  With a little impact to scheduling fairness, it may improve
+	  responsiveness especially under heavy background workload.
+
+	  You can turn it off by setting the sysctl kernel.sched_bore = 0.
+	  Enabling this feature implies NO_GENTLE_FAIR_SLEEPERS by default.
+
+	  If unsure say Y here.
+
 config SCHED_AUTOGROUP
 	bool "Automatic process group scheduling"
 	select CGROUPS
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 3bcb77b00..65469bc43 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4490,6 +4490,57 @@ int wake_up_state(struct task_struct *p, unsigned int state)
 	return try_to_wake_up(p, state, 0);
 }
 
+#ifdef CONFIG_SCHED_BORE
+#define CHILD_BURST_CUTOFF_BITS 9
+extern unsigned int sched_burst_cache_lifetime;
+
+void __init sched_init_bore(void) {
+	init_task.child_burst_cache = 0;
+	init_task.child_burst_last_cached = 0;
+	init_task.se.prev_burst_time = 0;
+	init_task.se.burst_time = 0;
+	init_task.se.max_burst_time = 0;
+}
+
+void inline __sched_fork_bore(struct task_struct *p) {
+	p->child_burst_cache = 0;
+	p->child_burst_last_cached = 0;
+	p->se.burst_time = 0;
+}
+
+static inline void update_task_child_burst_time_cache(struct task_struct *p) {
+	u64 sum = 0, avg_burst_time = 0;
+	u32 cnt = 0;
+	struct task_struct *child;
+
+	read_lock(&tasklist_lock);
+	list_for_each_entry(child, &p->children, sibling) {
+		cnt++;
+		sum += child->se.max_burst_time >> CHILD_BURST_CUTOFF_BITS;
+	}
+	read_unlock(&tasklist_lock);
+
+	if (cnt) avg_burst_time = div_u64(sum, cnt) << CHILD_BURST_CUTOFF_BITS;
+	p->child_burst_cache = max(avg_burst_time, p->se.max_burst_time);
+}
+
+static void update_task_initial_burst_time(struct task_struct *task) {
+	struct sched_entity *se = &task->se;
+	struct task_struct *par = task->real_parent;
+	u64 ktime = ktime_to_ns(ktime_get());
+
+	if (likely(par)) {
+		if (par->child_burst_last_cached + sched_burst_cache_lifetime < ktime) {
+			par->child_burst_last_cached = ktime;
+			update_task_child_burst_time_cache(par);
+		}
+		se->prev_burst_time = max(se->prev_burst_time, par->child_burst_cache);
+	}
+
+	se->max_burst_time = se->prev_burst_time;
+}
+#endif // CONFIG_SCHED_BORE
+
 /*
  * Perform scheduler related setup for a newly forked process p.
  * p is forked by current.
@@ -4506,6 +4557,9 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
 	p->se.prev_sum_exec_runtime	= 0;
 	p->se.nr_migrations		= 0;
 	p->se.vruntime			= 0;
+#ifdef CONFIG_SCHED_BORE
+	__sched_fork_bore(p);
+#endif // CONFIG_SCHED_BORE
 	p->se.vlag			= 0;
 	INIT_LIST_HEAD(&p->se.group_node);
 
@@ -4735,6 +4789,9 @@ late_initcall(sched_core_sysctl_init);
 int sched_fork(unsigned long clone_flags, struct task_struct *p)
 {
 	__sched_fork(clone_flags, p);
+#ifdef CONFIG_SCHED_BORE
+	update_task_initial_burst_time(p);
+#endif // CONFIG_SCHED_BORE
 	/*
 	 * We mark the process as NEW here. This guarantees that
 	 * nobody will actually run it, and a signal or other external
@@ -9955,6 +10012,11 @@ void __init sched_init(void)
 	BUG_ON(&dl_sched_class != &stop_sched_class + 1);
 #endif
 
+#ifdef CONFIG_SCHED_BORE
+	sched_init_bore();
+	printk(KERN_INFO "BORE (Burst-Oriented Response Enhancer) CPU Scheduler modification 2.4.1 by Masahito Suzuki");
+#endif // CONFIG_SCHED_BORE
+
 	wait_bit_init();
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index e7e83181f..c29500314 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -348,6 +348,7 @@ static __init int sched_init_debug(void)
 #endif
 
 	debugfs_create_u32("base_slice_ns", 0644, debugfs_sched, &sysctl_sched_base_slice);
+	debugfs_create_u32("wakeup_granularity_ns", 0644, debugfs_sched, &sysctl_sched_wakeup_granularity);
 
 	debugfs_create_u32("latency_warn_ms", 0644, debugfs_sched, &sysctl_resched_latency_warn_ms);
 	debugfs_create_u32("latency_warn_once", 0644, debugfs_sched, &sysctl_resched_latency_warn_once);
@@ -594,6 +595,9 @@ print_task(struct seq_file *m, struct rq *rq, struct task_struct *p)
 		SPLIT_NS(schedstat_val_or_zero(p->stats.sum_sleep_runtime)),
 		SPLIT_NS(schedstat_val_or_zero(p->stats.sum_block_runtime)));
 
+#ifdef CONFIG_SCHED_BORE
+	SEQ_printf(m, " %2d", p->se.penalty_score);
+#endif
 #ifdef CONFIG_NUMA_BALANCING
 	SEQ_printf(m, " %d %d", task_node(p), task_numa_group_id(p));
 #endif
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 97678b9b4..c3d632800 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -19,6 +19,9 @@
  *
  *  Adaptive scheduling granularity, math enhancements by Peter Zijlstra
  *  Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra
+ *
+ *  Burst-Oriented Response Enhancer (BORE) CPU Scheduler
+ *  Copyright (C) 2021-2023 Masahito Suzuki <firelzrd@gmail.com>
  */
 #include <linux/energy_model.h>
 #include <linux/mmap_lock.h>
@@ -66,17 +69,17 @@
  *   SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
  *   SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
  *
- * (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
+ * (default SCHED_TUNABLESCALING_NONE = *1)
  */
-unsigned int sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_LOG;
+unsigned int sysctl_sched_tunable_scaling = SCHED_TUNABLESCALING_NONE;
 
 /*
  * Minimal preemption granularity for CPU-bound tasks:
  *
- * (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
+ * (default: 3 msec * 1, units: nanoseconds)
  */
-unsigned int sysctl_sched_base_slice			= 750000ULL;
-static unsigned int normalized_sysctl_sched_base_slice	= 750000ULL;
+unsigned int sysctl_sched_base_slice			= 3000000ULL;
+static unsigned int normalized_sysctl_sched_base_slice	= 3000000ULL;
 
 /*
  * After fork, child runs first. If set to 0 (default) then
@@ -84,8 +87,75 @@ static unsigned int normalized_sysctl_sched_base_slice	= 750000ULL;
  */
 unsigned int sysctl_sched_child_runs_first __read_mostly;
 
+/*
+ * SCHED_OTHER wake-up granularity.
+ *
+ * This option delays the preemption effects of decoupled workloads
+ * and reduces their over-scheduling. Synchronous workloads will still
+ * have immediate wakeup/sleep latencies.
+ *
+ * (default: 3.2 msec * 1, units: nanoseconds)
+ */
+unsigned int sysctl_sched_wakeup_granularity			= 3200000UL;
+static unsigned int normalized_sysctl_sched_wakeup_granularity	= 3200000UL;
+
 const_debug unsigned int sysctl_sched_migration_cost	= 500000UL;
 
+#ifdef CONFIG_SCHED_BORE
+unsigned int __read_mostly sched_bore                 = 1;
+unsigned int __read_mostly sched_burst_cache_lifetime = 15000000;
+unsigned int __read_mostly sched_burst_penalty_offset = 12;
+unsigned int __read_mostly sched_burst_penalty_scale  = 1292;
+unsigned int __read_mostly sched_burst_smoothness     = 1;
+static int three          = 3;
+static int sixty_four     = 64;
+static int maxval_12_bits = 4095;
+
+#define FIXED_SHIFT 10
+#define FIXED_ONE (1 << FIXED_SHIFT)
+typedef u32 fixed;
+
+static void update_burst_score(struct sched_entity *se) {
+	u64 burst_time = se->max_burst_time;
+
+	int msb = fls64(burst_time);
+	fixed integer_part = msb << FIXED_SHIFT;
+	fixed fractional_part = burst_time << (64 - msb) << 1 >> (64 - FIXED_SHIFT);
+	fixed greed = integer_part | fractional_part;
+
+	fixed tolerance = sched_burst_penalty_offset << FIXED_SHIFT;
+	fixed penalty = max(0, (s32)greed - (s32)tolerance);
+	fixed scaled_penalty = penalty * sched_burst_penalty_scale >> 10;
+
+	u8 score = min(39U, scaled_penalty >> FIXED_SHIFT);
+	se->penalty_score = score;
+}
+
+static inline u64 penalty_scale(u64 delta, struct sched_entity *se) {
+	return mul_u64_u32_shr(delta, sched_prio_to_wmult[se->penalty_score], 22);
+}
+
+static inline u64 __binary_smooth(u64 new, u64 old, unsigned int smoothness) {
+	return (new + old * ((1 << smoothness) - 1)) >> smoothness;
+}
+
+void restart_burst(struct sched_entity *se) {
+	se->max_burst_time = se->prev_burst_time = __binary_smooth(
+		se->burst_time, se->prev_burst_time, sched_burst_smoothness);
+	se->burst_time = 0;
+}
+
+#define calc_delta_fair(delta, se) __calc_delta_fair(delta, se, true)
+#define calc_delta_fair_unscaled(delta, se) __calc_delta_fair(delta, se, false)
+static inline u64
+__calc_delta_fair(u64 delta, struct sched_entity *se, bool bscale);
+
+static s64 wakeup_preempt_backstep_delta(u64 rtime, struct sched_entity *se) {
+	u64 delta = calc_delta_fair_unscaled(rtime, se);
+	return delta - penalty_scale(delta, se);
+}
+#endif // CONFIG_SCHED_BORE
+
 int sched_thermal_decay_shift;
 static int __init setup_sched_thermal_decay_shift(char *str)
 {
@@ -145,6 +215,51 @@ static unsigned int sysctl_numa_balancing_promote_rate_limit = 65536;
 
 #ifdef CONFIG_SYSCTL
 static struct ctl_table sched_fair_sysctls[] = {
+#ifdef CONFIG_SCHED_BORE
+	{
+		.procname	= "sched_bore",
+		.data		= &sched_bore,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= SYSCTL_ONE,
+	},
+	{
+		.procname	= "sched_burst_cache_lifetime",
+		.data		= &sched_burst_cache_lifetime,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler = proc_dointvec,
+	},
+	{
+		.procname	= "sched_burst_penalty_offset",
+		.data		= &sched_burst_penalty_offset,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= &sixty_four,
+	},
+	{
+		.procname	= "sched_burst_penalty_scale",
+		.data		= &sched_burst_penalty_scale,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= &maxval_12_bits,
+	},
+	{
+		.procname	= "sched_burst_smoothness",
+		.data		= &sched_burst_smoothness,
+		.maxlen		= sizeof(unsigned int),
+		.mode		= 0644,
+		.proc_handler	= &proc_dointvec_minmax,
+		.extra1		= SYSCTL_ZERO,
+		.extra2		= &three,
+	},
+#endif // CONFIG_SCHED_BORE
 	{
 		.procname       = "sched_child_runs_first",
 		.data           = &sysctl_sched_child_runs_first,
@@ -238,6 +353,7 @@ static void update_sysctl(void)
 #define SET_SYSCTL(name) \
 	(sysctl_##name = (factor) * normalized_sysctl_##name)
 	SET_SYSCTL(sched_base_slice);
+	SET_SYSCTL(sched_wakeup_granularity);
 #undef SET_SYSCTL
 }
 
@@ -308,11 +424,19 @@ static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight
 /*
  * delta /= w
  */
+#ifdef CONFIG_SCHED_BORE
+static inline u64
+__calc_delta_fair(u64 delta, struct sched_entity *se, bool bscale)
+#else // CONFIG_SCHED_BORE
 static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se)
+#endif // CONFIG_SCHED_BORE
 {
 	if (unlikely(se->load.weight != NICE_0_LOAD))
 		delta = __calc_delta(delta, NICE_0_LOAD, &se->load);
 
+#ifdef CONFIG_SCHED_BORE
+	if (bscale && likely(sched_bore)) delta = penalty_scale(delta, se);
+#endif // CONFIG_SCHED_BORE
 	return delta;
 }
 
@@ -708,7 +832,11 @@ void update_entity_lag(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	SCHED_WARN_ON(!se->on_rq);
 	lag = avg_vruntime(cfs_rq) - se->vruntime;
 
+#ifdef CONFIG_SCHED_BORE
+	limit = calc_delta_fair_unscaled(max_t(u64, 2*se->slice, TICK_NSEC), se);
+#else // CONFIG_SCHED_BORE
 	limit = calc_delta_fair(max_t(u64, 2*se->slice, TICK_NSEC), se);
+#endif // CONFIG_SCHED_BORE
 	se->vlag = clamp(lag, -limit, limit);
 }
 
@@ -946,6 +1074,7 @@ int sched_update_scaling(void)
 #define WRT_SYSCTL(name) \
 	(normalized_sysctl_##name = sysctl_##name / (factor))
 	WRT_SYSCTL(sched_base_slice);
+	WRT_SYSCTL(sched_wakeup_granularity);
 #undef WRT_SYSCTL
 
 	return 0;
@@ -1123,6 +1252,11 @@ static void update_curr(struct cfs_rq *cfs_rq)
 	curr->sum_exec_runtime += delta_exec;
 	schedstat_add(cfs_rq->exec_clock, delta_exec);
 
+#ifdef CONFIG_SCHED_BORE
+	curr->burst_time += delta_exec;
+	curr->max_burst_time = max(curr->max_burst_time, curr->burst_time);
+	update_burst_score(curr);
+#endif // CONFIG_SCHED_BORE
 	curr->vruntime += calc_delta_fair(delta_exec, curr);
 	update_deadline(cfs_rq, curr);
 	update_min_vruntime(cfs_rq);
@@ -5217,6 +5351,9 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
+static int
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
+
 /*
  * Pick the next process, keeping these things in mind, in this order:
  * 1) keep things fair between processes/task groups
@@ -5227,14 +5364,16 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 static struct sched_entity *
 pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 {
+	struct sched_entity *candidate = pick_eevdf(cfs_rq);
 	/*
 	 * Enabling NEXT_BUDDY will affect latency but not fairness.
 	 */
 	if (sched_feat(NEXT_BUDDY) &&
-	    cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next))
+	    cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next) &&
+			wakeup_preempt_entity(cfs_rq->next, candidate) < 1)
 		return cfs_rq->next;
 
-	return pick_eevdf(cfs_rq);
+	return candidate;
 }
 
 static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
@@ -6464,6 +6603,38 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	hrtick_update(rq);
 }
 
+static unsigned long wakeup_gran(struct sched_entity *se)
+{
+	unsigned long gran = sysctl_sched_wakeup_granularity;
+#ifdef CONFIG_SCHED_BORE
+	return calc_delta_fair_unscaled(gran, se);
+#else // CONFIG_SCHED_BORE
+	return calc_delta_fair(gran, se);
+#endif // CONFIG_SCHED_BORE
+}
+
+static int
+wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
+{
+	s64 gran, vdiff = curr->vruntime - se->vruntime;
+#ifdef CONFIG_SCHED_BORE
+	if (likely(sched_bore)) {
+		u64 rtime = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
+		vdiff += wakeup_preempt_backstep_delta(rtime, curr)
+		       - wakeup_preempt_backstep_delta(rtime, se);
+	}
+#endif // CONFIG_SCHED_BORE
+
+	if (vdiff <= 0)
+		return -1;
+
+	gran = wakeup_gran(se);
+	if (vdiff > gran)
+		return 1;
+
+	return 0;
+}
+
 static void set_next_buddy(struct sched_entity *se);
 
 /*
@@ -6482,6 +6653,9 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	util_est_dequeue(&rq->cfs, p);
 
 	for_each_sched_entity(se) {
+#ifdef CONFIG_SCHED_BORE
+		if (task_sleep) restart_burst(se);
+#endif // CONFIG_SCHED_BORE
 		cfs_rq = cfs_rq_of(se);
 		dequeue_entity(cfs_rq, se, flags);
 
@@ -7972,7 +8146,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
 	/*
 	 * XXX pick_eevdf(cfs_rq) != se ?
 	 */
-	if (pick_eevdf(cfs_rq) == pse)
+	if ((pick_eevdf(cfs_rq) == pse) && (wakeup_preempt_entity(se, pse) == 1))
 		goto preempt;
 
 	return;
@@ -8185,6 +8359,9 @@ static void yield_task_fair(struct rq *rq)
 	struct task_struct *curr = rq->curr;
 	struct cfs_rq *cfs_rq = task_cfs_rq(curr);
 	struct sched_entity *se = &curr->se;
+#ifdef CONFIG_SCHED_BORE
+	restart_burst(se);
+#endif // CONFIG_SCHED_BORE
 
 	/*
 	 * Are we the only task in the tree?
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index ca95044a7..a7d34d1b2 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -13,7 +13,11 @@ SCHED_FEAT(PLACE_DEADLINE_INITIAL, true)
  * wakeup-preemption), since its likely going to consume data we
  * touched, increases cache locality.
  */
+#ifdef CONFIG_SCHED_BORE
+SCHED_FEAT(NEXT_BUDDY, true)
+#else // CONFIG_SCHED_BORE
 SCHED_FEAT(NEXT_BUDDY, false)
+#endif // CONFIG_SCHED_BORE
 
 /*
  * Consider buddies to be cache hot, decreases the likeliness of a
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 0ea13cfac..34cb2fbbb 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2479,6 +2479,7 @@ extern const_debug unsigned int sysctl_sched_nr_migrate;
 extern const_debug unsigned int sysctl_sched_migration_cost;
 
 extern unsigned int sysctl_sched_base_slice;
+extern unsigned int sysctl_sched_wakeup_granularity;
 
 #ifdef CONFIG_SCHED_DEBUG
 extern int sysctl_resched_latency_warn_ms;
-- 
2.41.0