Re: [PATCH v2 3/3] blk-mq: optimise *end_request non-stat path

[Christoph Hellwig]

On Wed, Oct 13, 2021 at 09:57:13AM +0100, Pavel Begunkov wrote:
> We already have a blk_mq_need_time_stamp() check in
> __blk_mq_end_request() to get a timestamp, hide all the statistics
> accounting under it. It cuts some cycles for requests that don't need
> stats, and is free otherwise.

The transformation is a little non-obvious due to the checks hidden
inblk_mq_need_time_stamp, but after following all the spaghetti it does
looks like a correct transformation:

Reviewed-by: Christoph Hellwig <hch@xxxxxx>