nvmet: don't split large I/Os unconditionally

If we know that the I/O size exceeds our inline bio vec, no
point using it and split the rest to begin with. We could
in theory reuse the inline bio and only allocate the bio_vec,
but its really not worth optimizing for.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Sagi Grimberg 2018-09-28 15:40:43 -07:00 committed by Christoph Hellwig
parent 783f4a4408
commit 73383adfad
2 changed files with 8 additions and 2 deletions

View File

@ -58,7 +58,7 @@ static void nvmet_bio_done(struct bio *bio)
static void nvmet_bdev_execute_rw(struct nvmet_req *req)
{
int sg_cnt = req->sg_cnt;
struct bio *bio = &req->b.inline_bio;
struct bio *bio;
struct scatterlist *sg;
sector_t sector;
blk_qc_t cookie;
@ -81,7 +81,12 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
sector = le64_to_cpu(req->cmd->rw.slba);
sector <<= (req->ns->blksize_shift - 9);
bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
if (req->data_len <= NVMET_MAX_INLINE_DATA_LEN) {
bio = &req->b.inline_bio;
bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
} else {
bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
}
bio_set_dev(bio, req->ns->bdev);
bio->bi_iter.bi_sector = sector;
bio->bi_private = req;

View File

@ -264,6 +264,7 @@ struct nvmet_fabrics_ops {
};
#define NVMET_MAX_INLINE_BIOVEC 8
#define NVMET_MAX_INLINE_DATA_LEN NVMET_MAX_INLINE_BIOVEC * PAGE_SIZE
struct nvmet_req {
struct nvme_command *cmd;