Re: [PATCH v2 0/4] block: callback-based statistics

[Jens Axboe <axboe@fb.com>]

On 03/21/2017 11:56 AM, Omar Sandoval wrote:
> From: Omar Sandoval <osandov@fb.com>
> 
> This patchset generalizes the blk-stats infrastructure to allow users to
> register a callback to be called at a given time with the statistics of
> requests completed during that window. Writeback throttling and hybrid
> polling are converted to the new infrastructure. The new Kyber I/O
> scheduler uses this, as well (but it needs to be rebased on this v2).
> 
> The details are in patch 4, which is the actual conversion. Patches 1-3
> are preparation cleanups.
> 
> Changes since v1:
> 
> - Now the user can subdivide stats into arbitrary buckets. Both in-tree
>   users just do reads vs. writes, but we can extend poll based on
>   request size in the future
> - blk_stat_arm_callback() became blk_stat_activate_msecs() and
>   blk_stat_activate_nsecs()
> - The poll statistics are exposed in debugfs
> 
> Omar Sandoval (4):
>   block: remove extra calls to wbt_exit()
>   blk-stat: use READ and WRITE instead of BLK_STAT_{READ,WRITE}
>   blk-stat: move BLK_RQ_STAT_BATCH definition to blk-stat.c
>   blk-stat: convert to callback-based statistics reporting

Added for 4.12, thanks Omar. This is a nice improvement for the
writeback throttling as well, since solves the issues with
the stats and throttling having separate and unsynced windows.

-- 
Jens Axboe