In nvmet_passthru_execute_cmd() which is a high frequency function
it uses bio_alloc() which leads to memory allocation from the fs pool
for each I/O.
For NVMeoF nvmet_req we already have inline_bvec allocated as a part of
request allocation that can be used with preallocated bio when we
already know the size of request before bio allocation with bio_alloc(),
which we already do.
Introduce a bio member for the nvmet_req passthru anon union. In the
fast path, check if we can get away with inline bvec and bio from
nvmet_req with bio_init() call before actually allocating from the
bio_alloc().
This will be useful to avoid any new memory allocation under high
memory pressure situation and get rid of any extra work of
allocation (bio_alloc()) vs initialization (bio_init()) when
transfer len is < NVMET_MAX_INLINE_DATA_LEN that user can configure at
compile time.
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@xxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
drivers/nvme/target/nvmet.h | 1 +
drivers/nvme/target/passthru.c | 12 +++++++++---
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 2f9635273629..e89ec280e91a 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -332,6 +332,7 @@ struct nvmet_req {
struct work_struct work;
} f;
struct {
+ struct bio inline_bio;
struct request *rq;
struct work_struct work;
bool use_workqueue;
diff --git a/drivers/nvme/target/passthru.c b/drivers/nvme/target/passthru.c
index 2b24205ee79d..b9776fc8f08f 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -194,14 +194,20 @@ static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
if (req->sg_cnt > BIO_MAX_PAGES)
return -EINVAL;
- bio = bio_alloc(GFP_KERNEL, req->sg_cnt);
- bio->bi_end_io = bio_put;
+ if (req->transfer_len <= NVMET_MAX_INLINE_DATA_LEN) {
+ bio = &req->p.inline_bio;
+ bio_init(bio, req->inline_bvec, ARRAY_SIZE(req->inline_bvec));
+ } else {
+ bio = bio_alloc(GFP_KERNEL, min(req->sg_cnt, BIO_MAX_PAGES));
+ bio->bi_end_io = bio_put;
+ }
bio->bi_opf = req_op(rq);
for_each_sg(req->sg, sg, req->sg_cnt, i) {
if (bio_add_pc_page(rq->q, bio, sg_page(sg), sg->length,
sg->offset) < sg->length) {
- bio_put(bio);
+ if (bio != &req->p.inline_bio)
+ bio_put(bio);
return -EINVAL;
}
}
--
2.22.1
