On Mon, Nov 05, 2018 at 11:23:01AM +0100, Johannes Thumshirn wrote: > With drivers like iSer we are seeing a lot of bio splitting and smaller I/Os > being submitted to the driver. > > The root cause of this issue that the virtual boundary mask code does not take > into consideration that some of the memory segments in the SG list may have > come from a huge memory page that is being managed in the SG list as 4K I guess you mean something like 64K PAGE_SIZE, instead of huge page. > blocks. This means that many of the segments in the SG list will have an > offset into the page that is not 0 but will be a multiple of 4K. > > Cc: Jan Kara <jack@xxxxxxx> > Cc: Sagi Grimberg <sagi@xxxxxxxxxxx> > Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx> > --- > 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; The change should only make difference in case that PAGE_SIZE is bigger than 4K. If yes, please add the description in commit log. Thanks, Ming
