linux-pikaos-template/patches/0003-bore.patch

From d1d05832308e210422f7c52d052b026deb9fabf1 Mon Sep 17 00:00:00 2001
From: Peter Jung <admin@ptr1337.dev>
Date: Thu, 6 Apr 2023 19:12:01 +0200
Subject: [PATCH] bore

Signed-off-by: Peter Jung <admin@ptr1337.dev>
---
 include/linux/sched.h   |   6 ++
 init/Kconfig            |  20 ++++++
 kernel/sched/core.c     |  30 ++++++++
 kernel/sched/debug.c    |   3 +
 kernel/sched/fair.c     | 149 +++++++++++++++++++++++++++++++++++++++-
 kernel/sched/features.h |   8 +++
 6 files changed, 213 insertions(+), 3 deletions(-)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 63d242164b1a..39a046d6cf90 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -555,6 +555,12 @@ struct sched_entity {
 	u64				sum_exec_runtime;
 	u64				vruntime;
 	u64				prev_sum_exec_runtime;
+#ifdef CONFIG_SCHED_BORE
+	u64				prev_burst_time;
+	u64				burst_time;
+	u64				max_burst_time;
+	u8				penalty_score;
+#endif // CONFIG_SCHED_BORE
 
 	u64				nr_migrations;
 
diff --git a/init/Kconfig b/init/Kconfig
index 1fb5f313d18f..6595e5ed2416 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1285,6 +1285,26 @@ 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 0d18c3969f90..34db768f6ba8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -4418,6 +4418,22 @@ int wake_up_state(struct task_struct *p, unsigned int state)
 	return try_to_wake_up(p, state, 0);
 }
 
+#ifdef CONFIG_SCHED_BORE
+static inline void adjust_prev_burst(struct task_struct *p)
+{
+	u32 cnt = 0;
+	u64 sum = 0, avg = 0;
+	struct task_struct *sib;
+	list_for_each_entry(sib, &p->sibling, sibling) {
+		cnt++;
+		sum += sib->se.max_burst_time >> 8;
+	}
+	if (cnt) avg = div_u64(sum, cnt) << 8;
+	if (p->se.prev_burst_time < avg) p->se.prev_burst_time = avg;
+	p->se.max_burst_time = p->se.prev_burst_time;
+}
+#endif // CONFIG_SCHED_BORE
+
 /*
  * Perform scheduler related setup for a newly forked process p.
  * p is forked by current.
@@ -4434,6 +4450,9 @@ 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
+	p->se.burst_time      = 0;
+#endif // CONFIG_SCHED_BORE
 	INIT_LIST_HEAD(&p->se.group_node);
 
 #ifdef CONFIG_FAIR_GROUP_SCHED
@@ -4659,6 +4678,9 @@ 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
+	adjust_prev_burst(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
@@ -9126,6 +9148,10 @@ void __init init_idle(struct task_struct *idle, int cpu)
 
 	idle->__state = TASK_RUNNING;
 	idle->se.exec_start = sched_clock();
+#ifdef CONFIG_SCHED_BORE
+	idle->se.prev_burst_time = 0;
+	idle->se.max_burst_time = 0;
+#endif //CONFIG_SCHED_BORE
 	/*
 	 * PF_KTHREAD should already be set at this point; regardless, make it
 	 * look like a proper per-CPU kthread.
@@ -9793,6 +9819,10 @@ void __init sched_init(void)
 	BUG_ON(&dl_sched_class != &stop_sched_class + 1);
 #endif
 
+#ifdef CONFIG_SCHED_BORE
+	printk(KERN_INFO "BORE (Burst-Oriented Response Enhancer) CPU Scheduler modification 2.1.1 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 1637b65ba07a..752c43a9ff13 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -547,6 +547,9 @@ 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 6986ea31c984..ee461e4586ca 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>
@@ -126,6 +129,16 @@ static unsigned int normalized_sysctl_sched_wakeup_granularity	= 1000000UL;
 
 const_debug unsigned int sysctl_sched_migration_cost	= 500000UL;
 
+#ifdef CONFIG_SCHED_BORE
+unsigned int __read_mostly sched_bore                 = 3;
+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;
+#endif // CONFIG_SCHED_BORE
+
 int sched_thermal_decay_shift;
 static int __init setup_sched_thermal_decay_shift(char *str)
 {
@@ -185,6 +198,44 @@ 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		= &three,
+	},
+	{
+		.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,
@@ -891,6 +942,47 @@ static void update_tg_load_avg(struct cfs_rq *cfs_rq)
 }
 #endif /* CONFIG_SMP */
 
+#ifdef CONFIG_SCHED_BORE
+static inline u32 __calc_bits10(u64 burst_time) {
+	u32 bits = fls64(burst_time);
+	u32 fdigs = likely(bits) ? bits - 1 : 0;
+	return (bits << 10) | (burst_time << (64 - fdigs) >> 54);
+}
+
+static inline u32 __calc_burst_score(u32 bits10, u32 offset) {
+	u32 val10 = max((s32)0, (s32)bits10 - (s32)(offset << 10));
+	return min((u32)39, val10 * sched_burst_penalty_scale >> 20);
+}
+
+static void update_burst_score(struct sched_entity *se) {
+	u32 bits10 = __calc_bits10(se->max_burst_time);
+	se->penalty_score = __calc_burst_score(bits10, sched_burst_penalty_offset);
+}
+
+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 preempt_scale(
+	u64 delta, struct sched_entity *curr, struct sched_entity *se) {
+
+	u32 score = max(0, (s32)se->penalty_score - (s32)curr->penalty_score) >> 1;
+	return mul_u64_u32_shr(delta, sched_prio_to_wmult[min(39, 20 + score)], 22);
+}
+
+static inline u64 binary_smooth(u64 old, u64 new, unsigned int smoothness) {
+	return (new + old * ((1 << smoothness) - 1)) >> smoothness;
+}
+
+static void reset_burst(struct sched_entity *se) {
+	se->prev_burst_time = binary_smooth(
+		se->prev_burst_time, se->burst_time, sched_burst_smoothness);
+	se->burst_time = 0;
+
+	se->max_burst_time = se->prev_burst_time;
+}
+#endif // CONFIG_SCHED_BORE
+
 /*
  * Update the current task's runtime statistics.
  */
@@ -920,6 +1012,14 @@ 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);
+	if (sched_bore & 1)
+		curr->vruntime += penalty_scale(calc_delta_fair(delta_exec, curr), curr);
+	else
+#endif // CONFIG_SCHED_BORE
 	curr->vruntime += calc_delta_fair(delta_exec, curr);
 	update_min_vruntime(cfs_rq);
 
@@ -5013,8 +5113,14 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
 	se->prev_sum_exec_runtime = se->sum_exec_runtime;
 }
 
+#ifdef CONFIG_SCHED_BORE
+static int
+wakeup_preempt_entity_bscale(struct sched_entity *curr,
+                             struct sched_entity *se, bool do_scale);
+#else // CONFIG_SCHED_BORE
 static int
 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
+#endif // CONFIG_SCHED_BORE
 
 /*
  * Pick the next process, keeping these things in mind, in this order:
@@ -5053,16 +5159,34 @@ pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr)
 				second = curr;
 		}
 
+#ifdef CONFIG_SCHED_BORE
+		if (second && wakeup_preempt_entity_bscale(
+			second, left, sched_bore & 2) < 1)
+#else // CONFIG_SCHED_BORE
 		if (second && wakeup_preempt_entity(second, left) < 1)
+#endif // CONFIG_SCHED_BORE
 			se = second;
 	}
 
-	if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1) {
+#ifdef CONFIG_SCHED_BORE
+	if (cfs_rq->next && wakeup_preempt_entity_bscale(
+		cfs_rq->next, left, sched_bore & 2) < 1)
+#else // CONFIG_SCHED_BORE
+	if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
+#endif // CONFIG_SCHED_BORE
+	{
 		/*
 		 * Someone really wants this to run. If it's not unfair, run it.
 		 */
 		se = cfs_rq->next;
-	} else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1) {
+	}
+#ifdef CONFIG_SCHED_BORE
+	else if (cfs_rq->last && wakeup_preempt_entity_bscale(
+		cfs_rq->last, left, sched_bore & 2) < 1)
+#else // CONFIG_SCHED_BORE
+	else if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
+#endif // CONFIG_SCHED_BORE
+	{
 		/*
 		 * Prefer last buddy, try to return the CPU to a preempted task.
 		 */
@@ -6331,6 +6455,9 @@ 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) reset_burst(se);
+#endif // CONFIG_SCHED_BORE
 		cfs_rq = cfs_rq_of(se);
 		dequeue_entity(cfs_rq, se, flags);
 
@@ -7746,7 +7873,12 @@ static unsigned long wakeup_gran(struct sched_entity *se)
  *
  */
 static int
+#ifdef CONFIG_SCHED_BORE
+wakeup_preempt_entity_bscale(struct sched_entity *curr,
+                             struct sched_entity *se, bool do_scale)
+#else // CONFIG_SCHED_BORE
 wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
+#endif // CONFIG_SCHED_BORE
 {
 	s64 gran, vdiff = curr->vruntime - se->vruntime;
 
@@ -7754,6 +7886,9 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
 		return -1;
 
 	gran = wakeup_gran(se);
+#ifdef CONFIG_SCHED_BORE
+	if (do_scale) gran = preempt_scale(gran, curr, se);
+#endif // CONFIG_SCHED_BORE
 	if (vdiff > gran)
 		return 1;
 
@@ -7858,7 +7993,12 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_
 		return;
 
 	update_curr(cfs_rq_of(se));
-	if (wakeup_preempt_entity(se, pse) == 1) {
+#ifdef CONFIG_SCHED_BORE
+	if (wakeup_preempt_entity_bscale(se, pse, sched_bore & 2) == 1)
+#else // CONFIG_SCHED_BORE
+	if (wakeup_preempt_entity(se, pse) == 1)
+#endif // CONFIG_SCHED_BORE
+	{
 		/*
 		 * Bias pick_next to pick the sched entity that is
 		 * triggering this preemption.
@@ -8094,6 +8234,9 @@ 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
+	reset_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 ee7f23c76bd3..3115bde98211 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -4,7 +4,11 @@
  * them to run sooner, but does not allow tons of sleepers to
  * rip the spread apart.
  */
+#ifdef CONFIG_SCHED_BORE
+SCHED_FEAT(GENTLE_FAIR_SLEEPERS, false)
+#else // CONFIG_SCHED_BORE
 SCHED_FEAT(GENTLE_FAIR_SLEEPERS, true)
+#endif // CONFIG_SCHED_BORE
 
 /*
  * Place new tasks ahead so that they do not starve already running
@@ -17,7 +21,11 @@ SCHED_FEAT(START_DEBIT, 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
 
 /*
  * Prefer to schedule the task that ran last (when we did
-- 
2.40.0