From dab3902b19a0dd1668d0cc3e8e4b976b1ee8638c Mon Sep 17 00:00:00 2001 From: Chaitanya Kulkarni Date: Mon, 9 Nov 2020 18:24:05 -0800 Subject: [PATCH] nvmet: use inline bio for passthru fast path 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 Reviewed-by: Logan Gunthorpe Signed-off-by: Christoph Hellwig --- 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; } }