1 /* 2 * Block stat tracking code 3 * 4 * Copyright (C) 2016 Jens Axboe 5 */ 6 #include <linux/kernel.h> 7 #include <linux/rculist.h> 8 #include <linux/blk-mq.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 bool enable_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 (!src->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; 56 u64 value; 57 58 value = (now >= rq->io_start_time_ns) ? now - rq->io_start_time_ns : 0; 59 60 blk_throtl_stat_add(rq, value); 61 62 rcu_read_lock(); 63 list_for_each_entry_rcu(cb, &q->stats->callbacks, list) { 64 if (!blk_stat_is_active(cb)) 65 continue; 66 67 bucket = cb->bucket_fn(rq); 68 if (bucket < 0) 69 continue; 70 71 stat = &get_cpu_ptr(cb->cpu_stat)[bucket]; 72 blk_rq_stat_add(stat, value); 73 put_cpu_ptr(cb->cpu_stat); 74 } 75 rcu_read_unlock(); 76 } 77 78 static void blk_stat_timer_fn(struct timer_list *t) 79 { 80 struct blk_stat_callback *cb = from_timer(cb, t, timer); 81 unsigned int bucket; 82 int cpu; 83 84 for (bucket = 0; bucket < cb->buckets; bucket++) 85 blk_rq_stat_init(&cb->stat[bucket]); 86 87 for_each_online_cpu(cpu) { 88 struct blk_rq_stat *cpu_stat; 89 90 cpu_stat = per_cpu_ptr(cb->cpu_stat, cpu); 91 for (bucket = 0; bucket < cb->buckets; bucket++) { 92 blk_rq_stat_sum(&cb->stat[bucket], &cpu_stat[bucket]); 93 blk_rq_stat_init(&cpu_stat[bucket]); 94 } 95 } 96 97 cb->timer_fn(cb); 98 } 99 100 struct blk_stat_callback * 101 blk_stat_alloc_callback(void (*timer_fn)(struct blk_stat_callback *), 102 int (*bucket_fn)(const struct request *), 103 unsigned int buckets, void *data) 104 { 105 struct blk_stat_callback *cb; 106 107 cb = kmalloc(sizeof(*cb), GFP_KERNEL); 108 if (!cb) 109 return NULL; 110 111 cb->stat = kmalloc_array(buckets, sizeof(struct blk_rq_stat), 112 GFP_KERNEL); 113 if (!cb->stat) { 114 kfree(cb); 115 return NULL; 116 } 117 cb->cpu_stat = __alloc_percpu(buckets * sizeof(struct blk_rq_stat), 118 __alignof__(struct blk_rq_stat)); 119 if (!cb->cpu_stat) { 120 kfree(cb->stat); 121 kfree(cb); 122 return NULL; 123 } 124 125 cb->timer_fn = timer_fn; 126 cb->bucket_fn = bucket_fn; 127 cb->data = data; 128 cb->buckets = buckets; 129 timer_setup(&cb->timer, blk_stat_timer_fn, 0); 130 131 return cb; 132 } 133 134 void blk_stat_add_callback(struct request_queue *q, 135 struct blk_stat_callback *cb) 136 { 137 unsigned int bucket; 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(&q->stats->lock); 149 list_add_tail_rcu(&cb->list, &q->stats->callbacks); 150 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 151 spin_unlock(&q->stats->lock); 152 } 153 154 void blk_stat_remove_callback(struct request_queue *q, 155 struct blk_stat_callback *cb) 156 { 157 spin_lock(&q->stats->lock); 158 list_del_rcu(&cb->list); 159 if (list_empty(&q->stats->callbacks) && !q->stats->enable_accounting) 160 blk_queue_flag_clear(QUEUE_FLAG_STATS, q); 161 spin_unlock(&q->stats->lock); 162 163 del_timer_sync(&cb->timer); 164 } 165 166 static void blk_stat_free_callback_rcu(struct rcu_head *head) 167 { 168 struct blk_stat_callback *cb; 169 170 cb = container_of(head, struct blk_stat_callback, rcu); 171 free_percpu(cb->cpu_stat); 172 kfree(cb->stat); 173 kfree(cb); 174 } 175 176 void blk_stat_free_callback(struct blk_stat_callback *cb) 177 { 178 if (cb) 179 call_rcu(&cb->rcu, blk_stat_free_callback_rcu); 180 } 181 182 void blk_stat_enable_accounting(struct request_queue *q) 183 { 184 spin_lock(&q->stats->lock); 185 q->stats->enable_accounting = true; 186 blk_queue_flag_set(QUEUE_FLAG_STATS, q); 187 spin_unlock(&q->stats->lock); 188 } 189 EXPORT_SYMBOL_GPL(blk_stat_enable_accounting); 190 191 struct blk_queue_stats *blk_alloc_queue_stats(void) 192 { 193 struct blk_queue_stats *stats; 194 195 stats = kmalloc(sizeof(*stats), GFP_KERNEL); 196 if (!stats) 197 return NULL; 198 199 INIT_LIST_HEAD(&stats->callbacks); 200 spin_lock_init(&stats->lock); 201 stats->enable_accounting = false; 202 203 return stats; 204 } 205 206 void blk_free_queue_stats(struct blk_queue_stats *stats) 207 { 208 if (!stats) 209 return; 210 211 WARN_ON(!list_empty(&stats->callbacks)); 212 213 kfree(stats); 214 } 215