With drivers that are settting a virtual boundary constrain, we are seeing a lot of bio splitting and smaller I/Os being submitted to the driver.
This happens because the bio gap detection code does not account cases where PAGE_SIZE - 1 is bigger than queue_virt_boundary() and thus will split the bio unnecessarily. Cc: Jan Kara <[email protected]> Cc: Sagi Grimberg <[email protected]> Cc: Bart Van Assche <[email protected]> Cc: Ming Lei <[email protected]> Signed-off-by: Johannes Thumshirn <[email protected]> Acked-by: Keith Busch <[email protected]> Reviewed-by: Ming Lei <[email protected]> --- Changes to v1: * Tried to re-phrase the commit message * Add reviews --- block/blk-merge.c | 2 +- block/blk.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/block/blk-merge.c b/block/blk-merge.c index 6b5ad275ed56..208658a901c6 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -46,7 +46,7 @@ static inline bool bio_will_gap(struct request_queue *q, bio_get_first_bvec(prev_rq->bio, &pb); else bio_get_first_bvec(prev, &pb); - if (pb.bv_offset) + if (pb.bv_offset & queue_virt_boundary(q)) return true; /* diff --git a/block/blk.h b/block/blk.h index a1841b8ff129..c85e53f21cdd 100644 --- a/block/blk.h +++ b/block/blk.h @@ -169,7 +169,7 @@ static inline bool biovec_phys_mergeable(struct request_queue *q, static inline bool __bvec_gap_to_prev(struct request_queue *q, struct bio_vec *bprv, unsigned int offset) { - return offset || + return (offset & queue_virt_boundary(q)) || ((bprv->bv_offset + bprv->bv_len) & queue_virt_boundary(q)); } -- 2.16.4
