diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 2eae67cd2ba2..fe569539e888 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -670,6 +670,16 @@ static __init int sched_init_debug(void) llc = debugfs_create_dir("llc_balancing", debugfs_sched); debugfs_create_file("enabled", 0644, llc, NULL, &sched_cache_enable_fops); + debugfs_create_u32("aggr_tolerance", 0644, llc, + &llc_aggr_tolerance); + debugfs_create_u32("epoch_period", 0644, llc, + &llc_epoch_period); + debugfs_create_u32("epoch_affinity_timeout", 0644, llc, + &llc_epoch_affinity_timeout); + debugfs_create_u32("overaggr_pct", 0644, llc, + &llc_overaggr_pct); + debugfs_create_u32("imb_pct", 0644, llc, + &llc_imb_pct); #endif debugfs_create_file("debug", 0444, debugfs_sched, NULL, &sched_debug_fops); diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index a10116ffe0d1..76ac6a8100fc 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1375,6 +1375,11 @@ static void set_next_buddy(struct sched_entity *se); */ #define EPOCH_PERIOD (HZ / 100) /* 10 ms */ #define EPOCH_LLC_AFFINITY_TIMEOUT 5 /* 50 ms */ +__read_mostly unsigned int llc_aggr_tolerance = 1; +__read_mostly unsigned int llc_epoch_period = EPOCH_PERIOD; +__read_mostly unsigned int llc_epoch_affinity_timeout = EPOCH_LLC_AFFINITY_TIMEOUT; +__read_mostly unsigned int llc_imb_pct = 20; +__read_mostly unsigned int llc_overaggr_pct = 50; static int llc_id(int cpu) { @@ -1384,11 +1389,25 @@ static int llc_id(int cpu) return per_cpu(sd_llc_id, cpu); } +static inline int get_sched_cache_scale(int mul) +{ + unsigned int tol = READ_ONCE(llc_aggr_tolerance); + + if (!tol) + return 0; + + if (tol >= 100) + return INT_MAX; + + return (1 + (tol - 1) * mul); +} + static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) { #ifdef CONFIG_NUMA_BALANCING unsigned long llc, footprint; struct sched_domain *sd; + int scale; guard(rcu)(); @@ -1404,7 +1423,28 @@ static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) llc = sd->llc_bytes; footprint = READ_ONCE(mm->sc_stat.footprint); - return (llc < (footprint * PAGE_SIZE)); + /* + * Scale the LLC size by 256*llc_aggr_tolerance + * and compare it to the task's footprint. + * + * Suppose the L3 size is 32MB. If the + * llc_aggr_tolerance is 1: + * When the footprint is larger than 32MB, the + * process is regarded as exceeding the LLC + * capacity. If the llc_aggr_tolerance is 99: + * When the footprint is larger than 784GB, the + * process is regarded as exceeding the LLC + * capacity: + * 784GB = (1 + (99 - 1) * 256) * 32MB + * If the llc_aggr_tolerance is 100: + * ignore the footprint and do the aggregation + * anyway. + */ + scale = get_sched_cache_scale(256); + if (scale == INT_MAX) + return false; + + return ((llc * (u64)scale) < (footprint * PAGE_SIZE)); } #endif return false; @@ -1413,11 +1453,21 @@ static bool exceed_llc_capacity(struct mm_struct *mm, int cpu) static bool invalid_llc_nr(struct mm_struct *mm, struct task_struct *p, int cpu) { + int scale; + if (get_nr_threads(p) <= 1) return true; + /* + * Scale the number of 'cores' in a LLC by llc_aggr_tolerance + * and compare it to the task's active threads. + */ + scale = get_sched_cache_scale(1); + if (scale == INT_MAX) + return false; + return !fits_capacity((mm->sc_stat.nr_running_avg * cpu_smt_num_threads), - per_cpu(sd_llc_size, cpu)); + (scale * per_cpu(sd_llc_size, cpu))); } static void account_llc_enqueue(struct rq *rq, struct task_struct *p) @@ -1513,13 +1563,14 @@ static inline void __update_mm_sched(struct rq *rq, { lockdep_assert_held(&rq->cpu_epoch_lock); + unsigned int period = max(READ_ONCE(llc_epoch_period), 1U); unsigned long n, now = jiffies; long delta = now - rq->cpu_epoch_next; if (delta > 0) { - n = (delta + EPOCH_PERIOD - 1) / EPOCH_PERIOD; + n = (delta + period - 1) / period; rq->cpu_epoch += n; - rq->cpu_epoch_next += n * EPOCH_PERIOD; + rq->cpu_epoch_next += n * period; __shr_u64(&rq->cpu_runtime, n); } @@ -1611,7 +1662,7 @@ void account_mm_sched(struct rq *rq, struct task_struct *p, s64 delta_exec) * If this process hasn't hit task_cache_work() for a while invalidate * its preferred state. */ - if (epoch - READ_ONCE(mm->sc_stat.epoch) > EPOCH_LLC_AFFINITY_TIMEOUT || + if ((long)(epoch - READ_ONCE(mm->sc_stat.epoch)) > llc_epoch_affinity_timeout || invalid_llc_nr(mm, p, cpu_of(rq)) || exceed_llc_capacity(mm, cpu_of(rq))) { if (mm->sc_stat.cpu != -1) @@ -1740,7 +1791,8 @@ static void task_cache_work(struct callback_head *work) /* only 1 thread is allowed to scan */ if (!try_cmpxchg(&mm->sc_stat.next_scan, &next_scan, - now + EPOCH_PERIOD)) + now + max_t(unsigned long, + READ_ONCE(llc_epoch_period), 1))) return; curr_cpu = task_cpu(p); @@ -10232,7 +10284,7 @@ static inline int task_is_ineligible_on_dst_cpu(struct task_struct *p, int dest_ */ static bool fits_llc_capacity(unsigned long util, unsigned long max) { - u32 aggr_pct = 50; + u32 aggr_pct = llc_overaggr_pct; /* * For single core systems, raise the aggregation @@ -10252,7 +10304,7 @@ static bool fits_llc_capacity(unsigned long util, unsigned long max) */ /* Allows dst util to be bigger than src util by up to bias percent */ #define util_greater(util1, util2) \ - ((util1) * 100 > (util2) * 120) + ((util1) * 100 > (util2) * (100 + llc_imb_pct)) static __maybe_unused bool get_llc_stats(int cpu, unsigned long *util, unsigned long *cap) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index f499d5dd1130..27409399137c 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -4072,6 +4072,11 @@ static inline void mm_cid_switch_to(struct task_struct *prev, struct task_struct DECLARE_STATIC_KEY_FALSE(sched_cache_present); DECLARE_STATIC_KEY_FALSE(sched_cache_active); extern int sysctl_sched_cache_user; +extern unsigned int llc_aggr_tolerance; +extern unsigned int llc_epoch_period; +extern unsigned int llc_epoch_affinity_timeout; +extern unsigned int llc_imb_pct; +extern unsigned int llc_overaggr_pct; static inline bool sched_cache_enabled(void) {