1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Block stat tracking code 4 * 5 * Copyright (C) 2016 Jens Axboe 6 */ 7 #include <linux/kernel.h> 8 #include <linux/rculist.h> 9 #include <linux/blk-mq.h> 10 11 #include "blk-stat.h" 12 #include "blk-mq.h" 13 #include "blk.h" 14 15 struct blk_queue_stats { 16 struct list_head callbacks; 17 spinlock_t lock; 18 bool enable_accounting; 19 }; 20 21 void blk_rq_stat_init(struct blk_rq_stat *stat) 22 { 23 stat->min = -1ULL; 24 stat->max = stat->nr_samples = stat->mean = 0; 25 stat->batch = 0; 26 } 27 28 /* src is a per-cpu stat, mean isn't initialized */ 29 void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) 30 { 31 if (!src->nr_samples) 32 return; 33 34 dst->min = min(dst->min, src->min); 35 dst->max = max(dst->max, src->max); 36 37 dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples, 38 dst->nr_samples + src->nr_samples); 39 40 dst->nr_samples += src->nr_samples; 41 } 42 43 void blk_rq_stat_add(struct blk_rq_stat *stat, u64 value) 44 { 45 stat->min = min(stat->min, value); 46 stat->max = max(stat->max, value); 47 stat->batch += value; 48 stat->nr_samples++; 49 } 50 51 void blk_stat_add(struct request *rq, u64 now) 52 { 53 struct request_queue *q = rq->q; 54 struct blk_stat_callback *cb; 55 struct blk_rq_stat *stat; 56 int bucket; 57 u64 value; 58 59 value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0; 60 61 blk_throtl_stat_add(rq, value); 62 63 rcu_read_lock(); 64 list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { 65 if (!blk_stat_is_active(cb)) 66 continue; 67 68 bucket = cb->bucket_fn(rq); 69 if (bucket < 0) 70 continue; 71 72 stat = &get_cpu_ptr(cb->cpu_stat)[bucket]; 73 blk_rq_stat_add(stat, value); 74 put_cpu_ptr(cb->cpu_stat); 75 } 76 rcu_read_unlock(); 77 } 78 79 static void blk_stat_timer_fn(struct timer_list *t) 80 { 81 struct blk_stat_callback *cb = from_timer(cb, t, timer); 82 unsigned int bucket; 83 int cpu; 84 85 for (bucket = 0; bucket < cb->buckets; bucket++) 86 blk_rq_stat_init(&cb->stat[bucket]); 87 88 for_each_online_cpu(cpu) { 89 struct blk_rq_stat *cpu_stat; 90 91 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 92 for (bucket = 0; bucket < cb->buckets; bucket++) { 93 blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); 94 blk_rq_stat_init(&cpu_stat[bucket]); 95 } 96 } 97 98 cb->timer_fn(cb); 99 } 100 101 struct blk_stat_callback * 102 blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), 103 int (*bucket_fn)(const struct request *), 104 unsigned int buckets, void *data) 105 { 106 struct blk_stat_callback *cb; 107 108 cb = kmalloc(sizeof(*cb), GFP_KERNEL); 109 if (!cb) 110 return NULL; 111 112 cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat), 113 GFP_KERNEL); 114 if (!cb->stat) { 115 kfree(cb); 116 return NULL; 117 } 118 cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat), 119 __alignof__(struct blk_rq_stat)); 120 if (!cb->cpu_stat) { 121 kfree(cb->stat); 122 kfree(cb); 123 return NULL; 124 } 125 126 cb->timer_fn = timer_fn; 127 cb->bucket_fn = bucket_fn; 128 cb->data = data; 129 cb->buckets = buckets; 130 timer_setup(&cb->timer, blk_stat_timer_fn, 0); 131 132 return cb; 133 } 134 135 void blk_stat_add_callback(struct request_queue *q, 136 struct blk_stat_callback *cb) 137 { 138 unsigned int bucket; 139 int cpu; 140 141 for_each_possible_cpu(cpu) { 142 struct blk_rq_stat *cpu_stat; 143 144 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 145 for (bucket = 0; bucket < cb->buckets; bucket++) 146 blk_rq_stat_init(&cpu_stat[bucket]); 147 } 148 149 spin_lock(&q->stats->lock); 150 list_add_tail_rcu(&cb->list, &q->stats->callbacks); 151 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 152 spin_unlock(&q->stats->lock); 153 } 154 155 void blk_stat_remove_callback(struct request_queue *q, 156 struct blk_stat_callback *cb) 157 { 158 spin_lock(&q->stats->lock); 159 list_del_rcu(&cb->list); 160 if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting) 161 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 162 spin_unlock(&q->stats->lock); 163 164 del_timer_sync(&cb->timer); 165 } 166 167 static void blk_stat_free_callback_rcu(struct rcu_head *head) 168 { 169 struct blk_stat_callback *cb; 170 171 cb = container_of(head, struct blk_stat_callback, rcu); 172 free_percpu(cb->cpu_stat); 173 kfree(cb->stat); 174 kfree(cb); 175 } 176 177 void blk_stat_free_callback(struct blk_stat_callback *cb) 178 { 179 if (cb) 180 call_rcu(&cb->rcu, blk_stat_free_callback_rcu); 181 } 182 183 void blk_stat_enable_accounting(struct request_queue *q) 184 { 185 spin_lock(&q->stats->lock); 186 q->stats->enable_accounting = true; 187 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 188 spin_unlock(&q->stats->lock); 189 } 190 EXPORT_SYMBOL_GPL(blk_stat_enable_accounting); 191 192 struct blk_queue_stats *blk_alloc_queue_stats(void) 193 { 194 struct blk_queue_stats *stats; 195 196 stats = kmalloc(sizeof(*stats), GFP_KERNEL); 197 if (!stats) 198 return NULL; 199 200 INIT_LIST_HEAD(&stats->callbacks); 201 spin_lock_init(&stats->lock); 202 stats->enable_accounting = false; 203 204 return stats; 205 } 206 207 void blk_free_queue_stats(struct blk_queue_stats *stats) 208 { 209 if (!stats) 210 return; 211 212 WARN_ON(!list_empty(&stats->callbacks)); 213 214 kfree(stats); 215 } 216