On Wed, Aug 01, 2018 at 04:54:02PM +0200, Christoph Hellwig wrote:
> We still hit __blk_recalc_rq_segments at least once per submission,
> don't we? Either rather wait with this until we have multi-page bvecs.
No.
Please see blk_queue_split(), where the physical segment number is
always updated, and the flag of BIO_SEG_VALID is set meantime.
And for callers of blk_recount_segments(), it will check the VALID flag
first, and blk_recount_segments() is only run when this flag isn't set.
blk_recount_segments
bio_phys_segments
ll_new_hw_segment
ll_back_merge_fn
ll_front_merge_fn
blk_rq_bio_prep
blk_rq_append_bio
blk_init_request_from_bio
bio_add_pc_page
ll_back_merge_fn
ll_front_merge_fn
Thanks,
Ming
