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 int 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 if (req_op(rq) == REQ_OP_READ || req_op(rq) == REQ_OP_WRITE) 62 blk_throtl_stat_add(rq, value); 63 64 rcu_read_lock(); 65 cpu = get_cpu(); 66 list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { 67 if (!blk_stat_is_active(cb)) 68 continue; 69 70 bucket = cb->bucket_fn(rq); 71 if (bucket < 0) 72 continue; 73 74 stat = &per_cpu_ptr(cb->cpu_stat, cpu)[bucket]; 75 blk_rq_stat_add(stat, value); 76 } 77 put_cpu(); 78 rcu_read_unlock(); 79 } 80 81 static void blk_stat_timer_fn(struct timer_list *t) 82 { 83 struct blk_stat_callback *cb = from_timer(cb, t, timer); 84 unsigned int bucket; 85 int cpu; 86 87 for (bucket = 0; bucket < cb->buckets; bucket++) 88 blk_rq_stat_init(&cb->stat[bucket]); 89 90 for_each_online_cpu(cpu) { 91 struct blk_rq_stat *cpu_stat; 92 93 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 94 for (bucket = 0; bucket < cb->buckets; bucket++) { 95 blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); 96 blk_rq_stat_init(&cpu_stat[bucket]); 97 } 98 } 99 100 cb->timer_fn(cb); 101 } 102 103 struct blk_stat_callback * 104 blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), 105 int (*bucket_fn)(const struct request *), 106 unsigned int buckets, void *data) 107 { 108 struct blk_stat_callback *cb; 109 110 cb = kmalloc(sizeof(*cb), GFP_KERNEL); 111 if (!cb) 112 return NULL; 113 114 cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat), 115 GFP_KERNEL); 116 if (!cb->stat) { 117 kfree(cb); 118 return NULL; 119 } 120 cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat), 121 __alignof__(struct blk_rq_stat)); 122 if (!cb->cpu_stat) { 123 kfree(cb->stat); 124 kfree(cb); 125 return NULL; 126 } 127 128 cb->timer_fn = timer_fn; 129 cb->bucket_fn = bucket_fn; 130 cb->data = data; 131 cb->buckets = buckets; 132 timer_setup(&cb->timer, blk_stat_timer_fn, 0); 133 134 return cb; 135 } 136 137 void blk_stat_add_callback(struct request_queue *q, 138 struct blk_stat_callback *cb) 139 { 140 unsigned int bucket; 141 unsigned long flags; 142 int cpu; 143 144 for_each_possible_cpu(cpu) { 145 struct blk_rq_stat *cpu_stat; 146 147 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 148 for (bucket = 0; bucket < cb->buckets; bucket++) 149 blk_rq_stat_init(&cpu_stat[bucket]); 150 } 151 152 spin_lock_irqsave(&q->stats->lock, flags); 153 list_add_tail_rcu(&cb->list, &q->stats->callbacks); 154 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 155 spin_unlock_irqrestore(&q->stats->lock, flags); 156 } 157 158 void blk_stat_remove_callback(struct request_queue *q, 159 struct blk_stat_callback *cb) 160 { 161 unsigned long flags; 162 163 spin_lock_irqsave(&q->stats->lock, flags); 164 list_del_rcu(&cb->list); 165 if (list_empty(&q->stats->callbacks) && !q->stats->accounting) 166 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 167 spin_unlock_irqrestore(&q->stats->lock, flags); 168 169 del_timer_sync(&cb->timer); 170 } 171 172 static void blk_stat_free_callback_rcu(struct rcu_head *head) 173 { 174 struct blk_stat_callback *cb; 175 176 cb = container_of(head, struct blk_stat_callback, rcu); 177 free_percpu(cb->cpu_stat); 178 kfree(cb->stat); 179 kfree(cb); 180 } 181 182 void blk_stat_free_callback(struct blk_stat_callback *cb) 183 { 184 if (cb) 185 call_rcu(&cb->rcu, blk_stat_free_callback_rcu); 186 } 187 188 void blk_stat_disable_accounting(struct request_queue *q) 189 { 190 unsigned long flags; 191 192 spin_lock_irqsave(&q->stats->lock, flags); 193 if (!--q->stats->accounting) 194 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 195 spin_unlock_irqrestore(&q->stats->lock, flags); 196 } 197 EXPORT_SYMBOL_GPL(blk_stat_disable_accounting); 198 199 void blk_stat_enable_accounting(struct request_queue *q) 200 { 201 unsigned long flags; 202 203 spin_lock_irqsave(&q->stats->lock, flags); 204 if (!q->stats->accounting++) 205 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 206 spin_unlock_irqrestore(&q->stats->lock, flags); 207 } 208 EXPORT_SYMBOL_GPL(blk_stat_enable_accounting); 209 210 struct blk_queue_stats *blk_alloc_queue_stats(void) 211 { 212 struct blk_queue_stats *stats; 213 214 stats = kmalloc(sizeof(*stats), GFP_KERNEL); 215 if (!stats) 216 return NULL; 217 218 INIT_LIST_HEAD(&stats->callbacks); 219 spin_lock_init(&stats->lock); 220 stats->accounting = 0; 221 222 return stats; 223 } 224 225 void blk_free_queue_stats(struct blk_queue_stats *stats) 226 { 227 if (!stats) 228 return; 229 230 WARN_ON(!list_empty(&stats->callbacks)); 231 232 kfree(stats); 233 } 234 235 bool blk_stats_alloc_enable(struct request_queue *q) 236 { 237 struct blk_rq_stat *poll_stat; 238 239 poll_stat = kcalloc(BLK_MQ_POLL_STATS_BKTS, sizeof(*poll_stat), 240 GFP_ATOMIC); 241 if (!poll_stat) 242 return false; 243 244 if (cmpxchg(&q->poll_stat, NULL, poll_stat) != NULL) { 245 kfree(poll_stat); 246 return true; 247 } 248 249 blk_stat_add_callback(q, q->poll_cb); 250 return false; 251 } 252