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 10 #include "blk-stat.h" 11 #include "blk-mq.h" 12 #include "blk.h" 13 14 struct blk_queue_stats { 15 struct list_head callbacks; 16 spinlock_t lock; 17 int accounting; 18 }; 19 20 void blk_rq_stat_init(struct blk_rq_stat *stat) 21 { 22 stat->min = -1ULL; 23 stat->max = stat->nr_samples = stat->mean = 0; 24 stat->batch = 0; 25 } 26 27 /* src is a per-cpu stat, mean isn't initialized */ 28 void blk_rq_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) 29 { 30 if (dst->nr_samples + src->nr_samples <= dst->nr_samples) 31 return; 32 33 dst->min = min(dst->min, src->min); 34 dst->max = max(dst->max, src->max); 35 36 dst->mean = div_u64(src->batch + dst->mean * dst->nr_samples, 37 dst->nr_samples + src->nr_samples); 38 39 dst->nr_samples += src->nr_samples; 40 } 41 42 void blk_rq_stat_add(struct blk_rq_stat *stat, u64 value) 43 { 44 stat->min = min(stat->min, value); 45 stat->max = max(stat->max, value); 46 stat->batch += value; 47 stat->nr_samples++; 48 } 49 50 void blk_stat_add(struct request *rq, u64 now) 51 { 52 struct request_queue *q = rq->q; 53 struct blk_stat_callback *cb; 54 struct blk_rq_stat *stat; 55 int bucket, cpu; 56 u64 value; 57 58 value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0; 59 60 rcu_read_lock(); 61 cpu = get_cpu(); 62 list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { 63 if (!blk_stat_is_active(cb)) 64 continue; 65 66 bucket = cb->bucket_fn(rq); 67 if (bucket < 0) 68 continue; 69 70 stat = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket]; 71 blk_rq_stat_add(stat, value); 72 } 73 put_cpu(); 74 rcu_read_unlock(); 75 } 76 77 static void blk_stat_timer_fn(struct timer_list *t) 78 { 79 struct blk_stat_callback *cb = from_timer(cb, t, timer); 80 unsigned int bucket; 81 int cpu; 82 83 for (bucket = 0; bucket < cb->buckets; bucket++) 84 blk_rq_stat_init(&cb->stat[bucket]); 85 86 for_each_online_cpu(cpu) { 87 struct blk_rq_stat *cpu_stat; 88 89 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 90 for (bucket = 0; bucket < cb->buckets; bucket++) { 91 blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); 92 blk_rq_stat_init(&cpu_stat[bucket]); 93 } 94 } 95 96 cb->timer_fn(cb); 97 } 98 99 struct blk_stat_callback * 100 blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), 101 int (*bucket_fn)(const struct request *), 102 unsigned int buckets, void *data) 103 { 104 struct blk_stat_callback *cb; 105 106 cb = kmalloc(sizeof(*cb), GFP_KERNEL); 107 if (!cb) 108 return NULL; 109 110 cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat), 111 GFP_KERNEL); 112 if (!cb->stat) { 113 kfree(cb); 114 return NULL; 115 } 116 cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat), 117 __alignof__(struct blk_rq_stat)); 118 if (!cb->cpu_stat) { 119 kfree(cb->stat); 120 kfree(cb); 121 return NULL; 122 } 123 124 cb->timer_fn = timer_fn; 125 cb->bucket_fn = bucket_fn; 126 cb->data = data; 127 cb->buckets = buckets; 128 timer_setup(&cb->timer, blk_stat_timer_fn, 0); 129 130 return cb; 131 } 132 133 void blk_stat_add_callback(struct request_queue *q, 134 struct blk_stat_callback *cb) 135 { 136 unsigned int bucket; 137 unsigned long flags; 138 int cpu; 139 140 for_each_possible_cpu(cpu) { 141 struct blk_rq_stat *cpu_stat; 142 143 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 144 for (bucket = 0; bucket < cb->buckets; bucket++) 145 blk_rq_stat_init(&cpu_stat[bucket]); 146 } 147 148 spin_lock_irqsave(&q->stats->lock, flags); 149 list_add_tail_rcu(&cb->list, &q->stats->callbacks); 150 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 151 spin_unlock_irqrestore(&q->stats->lock, flags); 152 } 153 154 void blk_stat_remove_callback(struct request_queue *q, 155 struct blk_stat_callback *cb) 156 { 157 unsigned long flags; 158 159 spin_lock_irqsave(&q->stats->lock, flags); 160 list_del_rcu(&cb->list); 161 if (list_empty(&q->stats->callbacks) && !q->stats->accounting) 162 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 163 spin_unlock_irqrestore(&q->stats->lock, flags); 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_disable_accounting(struct request_queue *q) 185 { 186 unsigned long flags; 187 188 spin_lock_irqsave(&q->stats->lock, flags); 189 if (!--q->stats->accounting && list_empty(&q->stats->callbacks)) 190 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 191 spin_unlock_irqrestore(&q->stats->lock, flags); 192 } 193 EXPORT_SYMBOL_GPL(blk_stat_disable_accounting); 194 195 void blk_stat_enable_accounting(struct request_queue *q) 196 { 197 unsigned long flags; 198 199 spin_lock_irqsave(&q->stats->lock, flags); 200 if (!q->stats->accounting++ && list_empty(&q->stats->callbacks)) 201 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 202 spin_unlock_irqrestore(&q->stats->lock, flags); 203 } 204 EXPORT_SYMBOL_GPL(blk_stat_enable_accounting); 205 206 struct blk_queue_stats *blk_alloc_queue_stats(void) 207 { 208 struct blk_queue_stats *stats; 209 210 stats = kmalloc(sizeof(*stats), GFP_KERNEL); 211 if (!stats) 212 return NULL; 213 214 INIT_LIST_HEAD(&stats->callbacks); 215 spin_lock_init(&stats->lock); 216 stats->accounting = 0; 217 218 return stats; 219 } 220 221 void blk_free_queue_stats(struct blk_queue_stats *stats) 222 { 223 if (!stats) 224 return; 225 226 WARN_ON(!list_empty(&stats->callbacks)); 227 228 kfree(stats); 229 } 230