Hi Jens,

This version has below changes:

1. remove BLK_ADDITIONAL_DISKSTAT option per Christoph's comment.
2. move blk_queue_io_extra_stat into blk_additional_{latency,sector}
   per Christoph's comment.
3. simplify blk_additional_latency by pass duration time directly.

Thanks,
Guoqing


PATCH V1: https://marc.info/?l=linux-block&m=161176000024443&w=2
* add Jack's reviewed-by.

RFC V4: https://marc.info/?l=linux-block&m=161027198729158&w=2
* rebase with latest code.

RFC V3: https://marc.info/?l=linux-block&m=159730633416534&w=2
* Move the #ifdef CONFIG_BLK_ADDITIONAL_DISKSTAT into the function body
  per Johannes's comment.
* Tweak the output of two tables to make they are more intuitive

RFC V2: https://marc.info/?l=linux-block&m=159467483514062&w=2
* don't call ktime_get_ns and drop unnecessary patches.
* add io_extra_stats to avoid potential overhead.

RFC V1: https://marc.info/?l=linux-block&m=159419516730386&w=2

Guoqing Jiang (4):
  block: add a statistic table for io latency
  block: add a statistic table for io sector
  block: add io_extra_stats node
  block: call blk_additional_{latency,sector} only when io_extra_stats
    is true

 Documentation/ABI/testing/sysfs-block | 26 ++++++++++
 Documentation/block/queue-sysfs.rst   |  5 ++
 block/blk-core.c                      | 43 ++++++++++++++++
 block/blk-sysfs.c                     |  3 ++
 block/genhd.c                         | 74 +++++++++++++++++++++++++++
 include/linux/blkdev.h                |  2 +
 include/linux/part_stat.h             |  6 +++
 7 files changed, 159 insertions(+)

-- 
2.17.1