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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7cd54aa843
Everytime we need to read ->nr_samples, we should have flushed the batch first. The non-mq read path also needs to flush the batch. Signed-off-by: Jens Axboe <axboe@fb.com>
257 lines
5.9 KiB
C
257 lines
5.9 KiB
C
/*
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* Block stat tracking code
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*
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* Copyright (C) 2016 Jens Axboe
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*/
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#include <linux/kernel.h>
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#include <linux/blk-mq.h>
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#include "blk-stat.h"
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#include "blk-mq.h"
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static void blk_stat_flush_batch(struct blk_rq_stat *stat)
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{
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const s32 nr_batch = READ_ONCE(stat->nr_batch);
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const s32 nr_samples = READ_ONCE(stat->nr_samples);
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if (!nr_batch)
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return;
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if (!nr_samples)
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stat->mean = div64_s64(stat->batch, nr_batch);
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else {
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stat->mean = div64_s64((stat->mean * nr_samples) +
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stat->batch,
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nr_batch + nr_samples);
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}
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stat->nr_samples += nr_batch;
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stat->nr_batch = stat->batch = 0;
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}
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static void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
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{
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if (!src->nr_samples)
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return;
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blk_stat_flush_batch(src);
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dst->min = min(dst->min, src->min);
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dst->max = max(dst->max, src->max);
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if (!dst->nr_samples)
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dst->mean = src->mean;
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else {
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dst->mean = div64_s64((src->mean * src->nr_samples) +
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(dst->mean * dst->nr_samples),
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dst->nr_samples + src->nr_samples);
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}
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dst->nr_samples += src->nr_samples;
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}
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static void blk_mq_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
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{
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struct blk_mq_hw_ctx *hctx;
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struct blk_mq_ctx *ctx;
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uint64_t latest = 0;
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int i, j, nr;
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blk_stat_init(&dst[BLK_STAT_READ]);
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blk_stat_init(&dst[BLK_STAT_WRITE]);
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nr = 0;
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do {
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uint64_t newest = 0;
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queue_for_each_hw_ctx(q, hctx, i) {
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hctx_for_each_ctx(hctx, ctx, j) {
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blk_stat_flush_batch(&ctx->stat[BLK_STAT_READ]);
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blk_stat_flush_batch(&ctx->stat[BLK_STAT_WRITE]);
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if (!ctx->stat[BLK_STAT_READ].nr_samples &&
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!ctx->stat[BLK_STAT_WRITE].nr_samples)
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continue;
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if (ctx->stat[BLK_STAT_READ].time > newest)
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newest = ctx->stat[BLK_STAT_READ].time;
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if (ctx->stat[BLK_STAT_WRITE].time > newest)
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newest = ctx->stat[BLK_STAT_WRITE].time;
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}
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}
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/*
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* No samples
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*/
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if (!newest)
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break;
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if (newest > latest)
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latest = newest;
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queue_for_each_hw_ctx(q, hctx, i) {
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hctx_for_each_ctx(hctx, ctx, j) {
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if (ctx->stat[BLK_STAT_READ].time == newest) {
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blk_stat_sum(&dst[BLK_STAT_READ],
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&ctx->stat[BLK_STAT_READ]);
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nr++;
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}
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if (ctx->stat[BLK_STAT_WRITE].time == newest) {
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blk_stat_sum(&dst[BLK_STAT_WRITE],
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&ctx->stat[BLK_STAT_WRITE]);
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nr++;
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}
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}
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}
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/*
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* If we race on finding an entry, just loop back again.
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* Should be very rare.
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*/
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} while (!nr);
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dst[BLK_STAT_READ].time = dst[BLK_STAT_WRITE].time = latest;
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}
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void blk_queue_stat_get(struct request_queue *q, struct blk_rq_stat *dst)
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{
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if (q->mq_ops)
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blk_mq_stat_get(q, dst);
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else {
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blk_stat_flush_batch(&q->rq_stats[BLK_STAT_READ]);
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blk_stat_flush_batch(&q->rq_stats[BLK_STAT_WRITE]);
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memcpy(&dst[BLK_STAT_READ], &q->rq_stats[BLK_STAT_READ],
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sizeof(struct blk_rq_stat));
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memcpy(&dst[BLK_STAT_WRITE], &q->rq_stats[BLK_STAT_WRITE],
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sizeof(struct blk_rq_stat));
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}
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}
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void blk_hctx_stat_get(struct blk_mq_hw_ctx *hctx, struct blk_rq_stat *dst)
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{
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struct blk_mq_ctx *ctx;
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unsigned int i, nr;
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nr = 0;
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do {
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uint64_t newest = 0;
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hctx_for_each_ctx(hctx, ctx, i) {
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blk_stat_flush_batch(&ctx->stat[BLK_STAT_READ]);
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blk_stat_flush_batch(&ctx->stat[BLK_STAT_WRITE]);
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if (!ctx->stat[BLK_STAT_READ].nr_samples &&
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!ctx->stat[BLK_STAT_WRITE].nr_samples)
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continue;
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if (ctx->stat[BLK_STAT_READ].time > newest)
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newest = ctx->stat[BLK_STAT_READ].time;
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if (ctx->stat[BLK_STAT_WRITE].time > newest)
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newest = ctx->stat[BLK_STAT_WRITE].time;
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}
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if (!newest)
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break;
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hctx_for_each_ctx(hctx, ctx, i) {
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if (ctx->stat[BLK_STAT_READ].time == newest) {
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blk_stat_sum(&dst[BLK_STAT_READ],
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&ctx->stat[BLK_STAT_READ]);
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nr++;
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}
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if (ctx->stat[BLK_STAT_WRITE].time == newest) {
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blk_stat_sum(&dst[BLK_STAT_WRITE],
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&ctx->stat[BLK_STAT_WRITE]);
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nr++;
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}
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}
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/*
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* If we race on finding an entry, just loop back again.
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* Should be very rare, as the window is only updated
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* occasionally
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*/
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} while (!nr);
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}
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static void __blk_stat_init(struct blk_rq_stat *stat, s64 time_now)
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{
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stat->min = -1ULL;
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stat->max = stat->nr_samples = stat->mean = 0;
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stat->batch = stat->nr_batch = 0;
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stat->time = time_now & BLK_STAT_NSEC_MASK;
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}
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void blk_stat_init(struct blk_rq_stat *stat)
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{
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__blk_stat_init(stat, ktime_to_ns(ktime_get()));
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}
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static bool __blk_stat_is_current(struct blk_rq_stat *stat, s64 now)
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{
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return (now & BLK_STAT_NSEC_MASK) == (stat->time & BLK_STAT_NSEC_MASK);
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}
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bool blk_stat_is_current(struct blk_rq_stat *stat)
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{
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return __blk_stat_is_current(stat, ktime_to_ns(ktime_get()));
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}
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void blk_stat_add(struct blk_rq_stat *stat, struct request *rq)
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{
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s64 now, value;
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now = __blk_stat_time(ktime_to_ns(ktime_get()));
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if (now < blk_stat_time(&rq->issue_stat))
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return;
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if (!__blk_stat_is_current(stat, now))
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__blk_stat_init(stat, now);
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value = now - blk_stat_time(&rq->issue_stat);
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if (value > stat->max)
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stat->max = value;
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if (value < stat->min)
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stat->min = value;
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if (stat->batch + value < stat->batch ||
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stat->nr_batch + 1 == BLK_RQ_STAT_BATCH)
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blk_stat_flush_batch(stat);
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stat->batch += value;
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stat->nr_batch++;
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}
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void blk_stat_clear(struct request_queue *q)
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{
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if (q->mq_ops) {
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struct blk_mq_hw_ctx *hctx;
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struct blk_mq_ctx *ctx;
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int i, j;
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queue_for_each_hw_ctx(q, hctx, i) {
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hctx_for_each_ctx(hctx, ctx, j) {
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blk_stat_init(&ctx->stat[BLK_STAT_READ]);
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blk_stat_init(&ctx->stat[BLK_STAT_WRITE]);
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}
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}
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} else {
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blk_stat_init(&q->rq_stats[BLK_STAT_READ]);
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blk_stat_init(&q->rq_stats[BLK_STAT_WRITE]);
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}
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}
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void blk_stat_set_issue_time(struct blk_issue_stat *stat)
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{
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stat->time = (stat->time & BLK_STAT_MASK) |
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(ktime_to_ns(ktime_get()) & BLK_STAT_TIME_MASK);
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}
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/*
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* Enable stat tracking, return whether it was enabled
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*/
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bool blk_stat_enable(struct request_queue *q)
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{
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if (!test_bit(QUEUE_FLAG_STATS, &q->queue_flags)) {
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set_bit(QUEUE_FLAG_STATS, &q->queue_flags);
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return false;
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}
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return true;
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}
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