From: Stephen Bates <sbates@xxxxxxxxxxxx> Omar recently developed some patches for block layer stats that use callbacks to determine which bucket an IO should be considered for. At the same time there was discussion at LSF/MM that we might not want to consider all IO when generating stats for certain algorithms (e.g. IO completion polling) or to bucket them in a more optimal fashion. This set does two things. It makes the bucket callback for stats signed so we can now ignore IO that cause a negative to be returned from the bucket function. It then improves the IO polling latency estimations by bucketing stats based on IO size and direction. This patchset applies cleanly on 6809ef67eb7b4b68d (Merge branch 'for-4.12/block' into for-next) in Jens' for-next tree. I've lightly tested this using QEMU and a real NVMe low-latency device. I do not have performance number yet. Feedback would be appreciated! I am not *super* happy with how the bucketing by size is done. Any suggestions on how to improve this would be appreciated! Cc: Damien.LeMoal@xxxxxxx Cc: osandov@xxxxxxxxxxx Changes since v1: Dropped the cast in blk_stat_rq_ddir() as per Omar's suggestion. Moved to an array of buckets based on IO size rather than a filter as suggested by Jens and Damien. Stephen Bates (2): blk-stat: convert blk-stat bucket callback to signed blk-mq: Add a polling specific stats function block/blk-mq.c | 54 ++++++++++++++++++++++++++++++++++++++++++++---------- block/blk-stat.c | 6 ++++-- block/blk-stat.h | 9 +++++---- 3 files changed, 53 insertions(+), 16 deletions(-) -- 2.7.4
