Linux-libre 4.7.1-gnupck-4.7.1-gnu

1 files changed, 185 insertions, 0 deletions

diff --git a/block/blk-stat.c b/block/blk-stat.c
new file mode 100644
index 000000000..8e3974d87
--- /dev/null
+++ b/block/blk-stat.c
@@ -0,0 +1,185 @@
+/*
+ * 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"
+
+void blk_stat_sum(struct blk_rq_stat *dst, struct blk_rq_stat *src)
+{
+	if (!src->nr_samples)
+		return;
+
+	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;
+	int i, j, nr;
+
+	blk_stat_init(&dst[0]);
+	blk_stat_init(&dst[1]);
+
+	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[0].nr_samples &&
+				    !ctx->stat[1].nr_samples)
+					continue;
+				if (ctx->stat[0].time > newest)
+					newest = ctx->stat[0].time;
+				if (ctx->stat[1].time > newest)
+					newest = ctx->stat[1].time;
+			}
+		}
+
+		/*
+		 * No samples
+		 */
+		if (!newest)
+			break;
+
+		queue_for_each_hw_ctx(q, hctx, i) {
+			hctx_for_each_ctx(hctx, ctx, j) {
+				if (ctx->stat[0].time == newest) {
+					blk_stat_sum(&dst[0], &ctx->stat[0]);
+					nr++;
+				}
+				if (ctx->stat[1].time == newest) {
+					blk_stat_sum(&dst[1], &ctx->stat[1]);
+					nr++;
+				}
+			}
+		}
+		/*
+		 * If we race on finding an entry, just loop back again.
+		 * Should be very rare.
+		 */
+	} while (!nr);
+}
+
+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[0], &q->rq_stats[0], sizeof(struct blk_rq_stat));
+		memcpy(&dst[1], &q->rq_stats[1], 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[0].nr_samples &&
+			    !ctx->stat[1].nr_samples)
+				continue;
+
+			if (ctx->stat[0].time > newest)
+				newest = ctx->stat[0].time;
+			if (ctx->stat[1].time > newest)
+				newest = ctx->stat[1].time;
+		}
+
+		if (!newest)
+			break;
+
+		hctx_for_each_ctx(hctx, ctx, i) {
+			if (ctx->stat[0].time == newest) {
+				blk_stat_sum(&dst[0], &ctx->stat[0]);
+				nr++;
+			}
+			if (ctx->stat[1].time == newest) {
+				blk_stat_sum(&dst[1], &ctx->stat[1]);
+				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->time = time_now & BLK_STAT_MASK;
+}
+
+void blk_stat_init(struct blk_rq_stat *stat)
+{
+	__blk_stat_init(stat, ktime_to_ns(ktime_get()));
+}
+
+void blk_stat_add(struct blk_rq_stat *stat, struct request *rq)
+{
+	s64 delta, now, value;
+	u64 rq_time = wbt_issue_stat_get_time(&rq->wb_stat);
+
+	now = ktime_to_ns(ktime_get());
+	if (now < rq_time)
+		return;
+
+	if ((now & BLK_STAT_MASK) != (stat->time & BLK_STAT_MASK))
+		__blk_stat_init(stat, now);
+
+	value = now - rq_time;
+	if (value > stat->max)
+		stat->max = value;
+	if (value < stat->min)
+		stat->min = value;
+
+	delta = value - stat->mean;
+	if (delta)
+		stat->mean += div64_s64(delta, stat->nr_samples + 1);
+
+	stat->nr_samples++;
+}
+
+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[0]);
+				blk_stat_init(&ctx->stat[1]);
+			}
+		}
+	} else {
+		blk_stat_init(&q->rq_stats[0]);
+		blk_stat_init(&q->rq_stats[1]);
+	}
+}