We currently account a '0' dispatch, and anything above that still falls
below the range set by BLK_MQ_MAX_DISPATCH_ORDER. If we dispatch more,
we don't account it.

Change the last bucket to be inclusive of anything above the range we
track, and have the sysfs file reflect that by including a '+' in the
output:

$ cat /sys/block/nvme0n1/mq/0/dispatched
       0        1006
       1        20229
       2        1
       4        0
       8        0
      16        0
      32+       0

Signed-off-by: Jens Axboe <[email protected]>

diff --git a/block/blk-mq-sysfs.c b/block/blk-mq-sysfs.c
index 885a4a59acd9..39840c37b7ce 100644
--- a/block/blk-mq-sysfs.c
+++ b/block/blk-mq-sysfs.c
@@ -208,12 +208,14 @@ static ssize_t blk_mq_hw_sysfs_dispatched_show(struct blk_mq_hw_ctx *hctx,

        page += sprintf(page, "%8u\t%lu\n", 0U, hctx->dispatched[0]);

-       for (i = 1; i < BLK_MQ_MAX_DISPATCH_ORDER; i++) {
-               unsigned long d = 1U << (i - 1);
+       for (i = 1; i < BLK_MQ_MAX_DISPATCH_ORDER - 1; i++) {
+               unsigned int d = 1U << (i - 1);

-               page += sprintf(page, "%8lu\t%lu\n", d, hctx->dispatched[i]);
+               page += sprintf(page, "%8u\t%lu\n", d, hctx->dispatched[i]);
        }

+       page += sprintf(page, "%8u+\t%lu\n", 1U << (i - 1),
+                                               hctx->dispatched[i]);
        return page - start_page;
 }

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4b8034e54478..fb4b6795ec57 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -802,6 +802,14 @@ static void flush_busy_ctxs(struct blk_mq_hw_ctx *hctx, struct list_head *list)
        }
 }

+static inline unsigned int queued_to_index(unsigned int queued)
+{
+       if (!queued)
+               return 0;
+
+       return min(BLK_MQ_MAX_DISPATCH_ORDER - 1, ilog2(queued) + 1);
+}
+
 /*
  * Run this hardware queue, pulling any software queues mapped to it in.
  * Note that this function currently has various problems around ordering
@@ -890,10 +898,7 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
                        dptr = &driver_list;
        }

-       if (!queued)
-               hctx->dispatched[0]++;
-       else if (queued < (1 << (BLK_MQ_MAX_DISPATCH_ORDER - 1)))
-               hctx->dispatched[ilog2(queued) + 1]++;
+       hctx->dispatched[queued_to_index(queued)]++;

        /*
         * Any items that need requeuing? Stuff them into hctx->dispatch,

--
Jens Axboe

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