Documentation/block/stat.rst

30 read merges     requests      number of read I/Os merged with in-queue I/O
32 read ticks      milliseconds  total wait time for read requests
33 write I/Os      requests      number of write I/Os processed
34 write merges    requests      number of write I/Os merged with in-queue I/O
35 write sectors   sectors       number of sectors written
36 write ticks     milliseconds  total wait time for write requests
39 time_in_queue   milliseconds  total wait time for all requests
41 discard merges  requests      number of discard I/Os merged with in-queue I/O
43 discard ticks   milliseconds  total wait time for discard requests
45 flush ticks     milliseconds  total wait time for flush requests
48 read I/Os, write I/Os, discard I/0s
61 read merges, write merges, discard merges
65 already-queued I/O request.
67 read sectors, write sectors, discard_sectors
72 standard UNIX 512-byte sectors, not any device- or filesystem-specific
75 read ticks, write ticks, discard ticks, flush ticks
79 waited on this block device.  If there are multiple I/O requests waiting,
81 example, if 60 read requests wait for an average of 30 ms, the read_ticks
101 on this block device.  If there are multiple I/O requests waiting, this