diff options
Diffstat (limited to 'block/blk-stat.c')
| -rw-r--r-- | block/blk-stat.c | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/block/blk-stat.c b/block/blk-stat.c new file mode 100644 index 000000000000..688c958367ee --- /dev/null +++ b/block/blk-stat.c @@ -0,0 +1,248 @@ +/* + * Block stat tracking code + * + * Copyright (C) 2016 Jens Axboe + */ +#include <linux/kernel.h> +#include <linux/blk-mq.h> + +#include "blk-stat.h" +#include "blk-mq.h" + +static void blk_stat_flush_batch(struct blk_rq_stat *stat) +{ + const s32 nr_batch = READ_ONCE(stat->nr_batch); + const s32 nr_samples = READ_ONCE(stat->nr_batch); + + if (!nr_batch) + return; + if (!nr_samples) + stat->mean = div64_s64(stat->batch, nr_batch); + else { + stat->mean = div64_s64((stat->mean * nr_samples) + + stat->batch, + nr_batch + nr_samples); + } + + stat->nr_samples += nr_batch; + stat->nr_batch = stat->batch = 0; +} + +static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src) +{ + if (!src->nr_samples) + return; + + blk_stat_flush_batch(src); + + dst->min = min(dst->min, src->min); + dst->max = max(dst->max, src->max); + + if (!dst->nr_samples) + dst->mean = src->mean; + else { + dst->mean = div64_s64((src->mean * src->nr_samples) + + (dst->mean * dst->nr_samples), + dst->nr_samples + src->nr_samples); + } + dst->nr_samples += src->nr_samples; +} + +static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst) +{ + struct blk_mq_hw_ctx *hctx; + struct blk_mq_ctx *ctx; + uint64_t latest = 0; + int i, j, nr; + + blk_stat_init(&dst[BLK_STAT_READ]); + blk_stat_init(&dst[BLK_STAT_WRITE]); + + nr = 0; + do { + uint64_t newest = 0; + + queue_for_each_hw_ctx(q, hctx, i) { + hctx_for_each_ctx(hctx, ctx, j) { + if (!ctx->stat[BLK_STAT_READ].nr_samples && + !ctx->stat[BLK_STAT_WRITE].nr_samples) + continue; + if (ctx->stat[BLK_STAT_READ].time > newest) + newest = ctx->stat[BLK_STAT_READ].time; + if (ctx->stat[BLK_STAT_WRITE].time > newest) + newest = ctx->stat[BLK_STAT_WRITE].time; + } + } + + /* + * No samples + */ + if (!newest) + break; + + if (newest > latest) + latest = newest; + + queue_for_each_hw_ctx(q, hctx, i) { + hctx_for_each_ctx(hctx, ctx, j) { + if (ctx->stat[BLK_STAT_READ].time == newest) { + blk_stat_sum(&dst[BLK_STAT_READ], + &ctx->stat[BLK_STAT_READ]); + nr++; + } + if (ctx->stat[BLK_STAT_WRITE].time == newest) { + blk_stat_sum(&dst[BLK_STAT_WRITE], + &ctx->stat[BLK_STAT_WRITE]); + nr++; + } + } + } + /* + * If we race on finding an entry, just loop back again. + * Should be very rare. + */ + } while (!nr); + + dst[BLK_STAT_READ].time = dst[BLK_STAT_WRITE].time = latest; +} + +void blk_queue_stat_get(struct request_queue *q, struct blk_rq_stat *dst) +{ + if (q->mq_ops) + blk_mq_stat_get(q, dst); + else { + memcpy(&dst[BLK_STAT_READ], &q->rq_stats[BLK_STAT_READ], + sizeof(struct blk_rq_stat)); + memcpy(&dst[BLK_STAT_WRITE], &q->rq_stats[BLK_STAT_WRITE], + sizeof(struct blk_rq_stat)); + } +} + +void blk_hctx_stat_get(struct blk_mq_hw_ctx *hctx, struct blk_rq_stat *dst) +{ + struct blk_mq_ctx *ctx; + unsigned int i, nr; + + nr = 0; + do { + uint64_t newest = 0; + + hctx_for_each_ctx(hctx, ctx, i) { + if (!ctx->stat[BLK_STAT_READ].nr_samples && + !ctx->stat[BLK_STAT_WRITE].nr_samples) + continue; + + if (ctx->stat[BLK_STAT_READ].time > newest) + newest = ctx->stat[BLK_STAT_READ].time; + if (ctx->stat[BLK_STAT_WRITE].time > newest) + newest = ctx->stat[BLK_STAT_WRITE].time; + } + + if (!newest) + break; + + hctx_for_each_ctx(hctx, ctx, i) { + if (ctx->stat[BLK_STAT_READ].time == newest) { + blk_stat_sum(&dst[BLK_STAT_READ], + &ctx->stat[BLK_STAT_READ]); + nr++; + } + if (ctx->stat[BLK_STAT_WRITE].time == newest) { + blk_stat_sum(&dst[BLK_STAT_WRITE], + &ctx->stat[BLK_STAT_WRITE]); + nr++; + } + } + /* + * If we race on finding an entry, just loop back again. + * Should be very rare, as the window is only updated + * occasionally + */ + } while (!nr); +} + +static void __blk_stat_init(struct blk_rq_stat *stat, s64 time_now) +{ + stat->min = -1ULL; + stat->max = stat->nr_samples = stat->mean = 0; + stat->batch = stat->nr_batch = 0; + stat->time = time_now & BLK_STAT_NSEC_MASK; +} + +void blk_stat_init(struct blk_rq_stat *stat) +{ + __blk_stat_init(stat, ktime_to_ns(ktime_get())); +} + +static bool __blk_stat_is_current(struct blk_rq_stat *stat, s64 now) +{ + return (now & BLK_STAT_NSEC_MASK) == (stat->time & BLK_STAT_NSEC_MASK); +} + +bool blk_stat_is_current(struct blk_rq_stat *stat) +{ + return __blk_stat_is_current(stat, ktime_to_ns(ktime_get())); +} + +void blk_stat_add(struct blk_rq_stat *stat, struct request *rq) +{ + s64 now, value; + + now = __blk_stat_time(ktime_to_ns(ktime_get())); + if (now < blk_stat_time(&rq->issue_stat)) + return; + + if (!__blk_stat_is_current(stat, now)) + __blk_stat_init(stat, now); + + value = now - blk_stat_time(&rq->issue_stat); + if (value > stat->max) + stat->max = value; + if (value < stat->min) + stat->min = value; + + if (stat->batch + value < stat->batch || + stat->nr_batch + 1 == BLK_RQ_STAT_BATCH) + blk_stat_flush_batch(stat); + + stat->batch += value; + stat->nr_batch++; +} + +void blk_stat_clear(struct request_queue *q) +{ + if (q->mq_ops) { + struct blk_mq_hw_ctx *hctx; + struct blk_mq_ctx *ctx; + int i, j; + + queue_for_each_hw_ctx(q, hctx, i) { + hctx_for_each_ctx(hctx, ctx, j) { + blk_stat_init(&ctx->stat[BLK_STAT_READ]); + blk_stat_init(&ctx->stat[BLK_STAT_WRITE]); + } + } + } else { + blk_stat_init(&q->rq_stats[BLK_STAT_READ]); + blk_stat_init(&q->rq_stats[BLK_STAT_WRITE]); + } +} + +void blk_stat_set_issue_time(struct blk_issue_stat *stat) +{ + stat->time = (stat->time & BLK_STAT_MASK) | + (ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK); +} + +/* + * Enable stat tracking, return whether it was enabled + */ +bool blk_stat_enable(struct request_queue *q) +{ + if (!test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) { + set_bit(QUEUE_FLAG_STATS, &q->queue_flags); + return false; + } + + return true; +} |