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, cpu; 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 cpu = get_cpu(); 65 list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { 66 if (!blk_stat_is_active(cb)) 67 continue; 68 69 bucket = cb->bucket_fn(rq); 70 if (bucket < 0) 71 continue; 72 73 stat = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket]; 74 blk_rq_stat_add(stat, value); 75 } 76 put_cpu(); 77 rcu_read_unlock(); 78 } 79 80 static void blk_stat_timer_fn(struct timer_list *t) 81 { 82 struct blk_stat_callback *cb = from_timer(cb, t, timer); 83 unsigned int bucket; 84 int cpu; 85 86 for (bucket = 0; bucket < cb->buckets; bucket++) 87 blk_rq_stat_init(&cb->stat[bucket]); 88 89 for_each_online_cpu(cpu) { 90 struct blk_rq_stat *cpu_stat; 91 92 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 93 for (bucket = 0; bucket < cb->buckets; bucket++) { 94 blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); 95 blk_rq_stat_init(&cpu_stat[bucket]); 96 } 97 } 98 99 cb->timer_fn(cb); 100 } 101 102 struct blk_stat_callback * 103 blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), 104 int (*bucket_fn)(const struct request *), 105 unsigned int buckets, void *data) 106 { 107 struct blk_stat_callback *cb; 108 109 cb = kmalloc(sizeof(*cb), GFP_KERNEL); 110 if (!cb) 111 return NULL; 112 113 cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat), 114 GFP_KERNEL); 115 if (!cb->stat) { 116 kfree(cb); 117 return NULL; 118 } 119 cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat), 120 __alignof__(struct blk_rq_stat)); 121 if (!cb->cpu_stat) { 122 kfree(cb->stat); 123 kfree(cb); 124 return NULL; 125 } 126 127 cb->timer_fn = timer_fn; 128 cb->bucket_fn = bucket_fn; 129 cb->data = data; 130 cb->buckets = buckets; 131 timer_setup(&cb->timer, blk_stat_timer_fn, 0); 132 133 return cb; 134 } 135 136 void blk_stat_add_callback(struct request_queue *q, 137 struct blk_stat_callback *cb) 138 { 139 unsigned int bucket; 140 int cpu; 141 142 for_each_possible_cpu(cpu) { 143 struct blk_rq_stat *cpu_stat; 144 145 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 146 for (bucket = 0; bucket < cb->buckets; bucket++) 147 blk_rq_stat_init(&cpu_stat[bucket]); 148 } 149 150 spin_lock(&q->stats->lock); 151 list_add_tail_rcu(&cb->list, &q->stats->callbacks); 152 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 153 spin_unlock(&q->stats->lock); 154 } 155 156 void blk_stat_remove_callback(struct request_queue *q, 157 struct blk_stat_callback *cb) 158 { 159 spin_lock(&q->stats->lock); 160 list_del_rcu(&cb->list); 161 if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting) 162 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 163 spin_unlock(&q->stats->lock); 164 165 del_timer_sync(&cb->timer); 166 } 167 168 static void blk_stat_free_callback_rcu(struct rcu_head *head) 169 { 170 struct blk_stat_callback *cb; 171 172 cb = container_of(head, struct blk_stat_callback, rcu); 173 free_percpu(cb->cpu_stat); 174 kfree(cb->stat); 175 kfree(cb); 176 } 177 178 void blk_stat_free_callback(struct blk_stat_callback *cb) 179 { 180 if (cb) 181 call_rcu(&cb->rcu, blk_stat_free_callback_rcu); 182 } 183 184 void blk_stat_enable_accounting(struct request_queue *q) 185 { 186 spin_lock(&q->stats->lock); 187 q->stats->enable_accounting = true; 188 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 189 spin_unlock(&q->stats->lock); 190 } 191 EXPORT_SYMBOL_GPL(blk_stat_enable_accounting); 192 193 struct blk_queue_stats *blk_alloc_queue_stats(void) 194 { 195 struct blk_queue_stats *stats; 196 197 stats = kmalloc(sizeof(*stats), GFP_KERNEL); 198 if (!stats) 199 return NULL; 200 201 INIT_LIST_HEAD(&stats->callbacks); 202 spin_lock_init(&stats->lock); 203 stats->enable_accounting = false; 204 205 return stats; 206 } 207 208 void blk_free_queue_stats(struct blk_queue_stats *stats) 209 { 210 if (!stats) 211 return; 212 213 WARN_ON(!list_empty(&stats->callbacks)); 214 215 kfree(stats); 216 } 217