From: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
To: linux-block@vger.kernel.org, linux-nvme@lists.infradead.org
Cc: kbusch@kernel.org, logang@deltatee.com, hch@lst.de,
Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>,
sagi@grimberg.me
Subject: [PATCH V3 6/6] nvmet: use inline bio for passthru fast path
Date: Wed, 21 Oct 2020 18:02:34 -0700 [thread overview]
Message-ID: <20201022010234.8304-7-chaitanya.kulkarni@wdc.com> (raw)
In-Reply-To: <20201022010234.8304-1-chaitanya.kulkarni@wdc.com>
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@wdc.com>
---
drivers/nvme/target/nvmet.h | 1 +
drivers/nvme/target/passthru.c | 20 ++++++++++++++++++--
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 559a15ccc322..408a13084fb4 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -330,6 +330,7 @@ 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 496ffedb77dc..32498b4302cc 100644
--- a/drivers/nvme/target/passthru.c
+++ b/drivers/nvme/target/passthru.c
@@ -178,6 +178,14 @@ static void nvmet_passthru_req_done(struct request *rq,
blk_mq_free_request(rq);
}
+static void nvmet_passthru_bio_done(struct bio *bio)
+{
+ struct nvmet_req *req = bio->bi_private;
+
+ if (bio != &req->p.inline_bio)
+ bio_put(bio);
+}
+
static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
{
int sg_cnt = req->sg_cnt;
@@ -186,13 +194,21 @@ static int nvmet_passthru_map_sg(struct nvmet_req *req, struct request *rq)
int i;
bio = bio_alloc(GFP_KERNEL, min(sg_cnt, BIO_MAX_PAGES));
- 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(sg_cnt, BIO_MAX_PAGES));
+ }
+
+ bio->bi_end_io = nvmet_passthru_bio_done;
bio->bi_opf = req_op(rq);
+ bio->bi_private = req;
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);
+ nvmet_passthru_bio_done(bio);
return -EINVAL;
}
sg_cnt--;
--
2.22.1
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next prev parent reply other threads:[~2020-10-22 1:03 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-22 1:02 [PATCH V3 0/6] nvmet: passthru fixes and improvements Chaitanya Kulkarni
2020-10-22 1:02 ` [PATCH V3 1/6] nvme-core: add a helper to init req from nvme cmd Chaitanya Kulkarni
2020-10-22 1:02 ` [PATCH V3 2/6] nvme-core: split nvme_alloc_request() Chaitanya Kulkarni
2020-11-03 18:24 ` Christoph Hellwig
2020-11-04 21:03 ` Chaitanya Kulkarni
2020-10-22 1:02 ` [PATCH V3 3/6] nvmet: remove op_flags for passthru commands Chaitanya Kulkarni
2020-10-22 1:02 ` [PATCH V3 4/6] block: move blk_rq_bio_prep() to linux/blk-mq.h Chaitanya Kulkarni
2020-10-22 1:02 ` [PATCH V3 5/6] nvmet: use minimized version of blk_rq_append_bio Chaitanya Kulkarni
2020-10-22 1:02 ` Chaitanya Kulkarni [this message]
2020-10-22 15:57 ` [PATCH V3 6/6] nvmet: use inline bio for passthru fast path Logan Gunthorpe
2020-10-29 19:02 ` Chaitanya Kulkarni
2020-11-03 18:25 ` hch
2020-11-03 18:32 ` [PATCH V3 0/6] nvmet: passthru fixes and improvements Christoph Hellwig
2020-11-03 23:50 ` Chaitanya Kulkarni
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