From d1d05832308e210422f7c52d052b026deb9fabf1 Mon Sep 17 00:00:00 2001 From: Peter Jung Date: Thu, 6 Apr 2023 19:12:01 +0200 Subject: [PATCH] bore Signed-off-by: Peter Jung --- 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 */ #include #include @@ -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