From: Christoph Hellwig <hch@lst.de>
Date: Mon, 28 Oct 2019 11:23:26 -0700
Subject: [PATCH] nvmet: add plugging for read/write when ns is bdev
Git-commit: 9dea0c81ee4a7b5d8e5bc0d4cfa2ee4f0e7b13f0
Patch-mainline: v5.5-rc1
References: bsc#1169045
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With reference to the following issue reported on the mailing list :-
http://lists.infradead.org/pipermail/linux-nvme/2019-October/027604.html
this patch adds plugging for the bdev-ns under nvmet_bdev_execute_rw().
We can see the following performance improvement in random write
workload I/Os with the setup described in the link when device_path
configured as /dev/md0.
Without this patch :-
write: IOPS=40.8k, BW=159MiB/s (167MB/s)(4777MiB/30002msec)
write: IOPS=41.2k, BW=161MiB/s (169MB/s)(4831MiB/30011msec)
slat (usec): min=8, max=10823, avg=15.64, stdev=16.85
slat (usec): min=8, max=401, avg=15.40, stdev= 9.56
clat (usec): min=54, max=2492, avg=759.07, stdev=172.62
clat (usec): min=56, max=1997, avg=768.06, stdev=178.72
With this patch :-
write: IOPS=123k, BW=480MiB/s (504MB/s)(14.1GiB/30011msec)
write: IOPS=123k, BW=481MiB/s (504MB/s)(14.1GiB/30002msec)
slat (usec): min=8, max=9941, avg=13.31, stdev= 8.04
slat (usec): min=8, max=289, avg=13.31, stdev= 3.37
clat (usec): min=43, max=17635, avg=245.46, stdev=171.23
clat (usec): min=44, max=17751, avg=245.25, stdev=183.14
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Hannes Reinecke <hare@suse.com>
---
drivers/nvme/target/io-cmd-bdev.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/nvme/target/io-cmd-bdev.c b/drivers/nvme/target/io-cmd-bdev.c
index 04a9cd2a2604..07e4f8c579d3 100644
--- a/drivers/nvme/target/io-cmd-bdev.c
+++ b/drivers/nvme/target/io-cmd-bdev.c
@@ -147,6 +147,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
int sg_cnt = req->sg_cnt;
struct bio *bio;
struct scatterlist *sg;
+ struct blk_plug plug;
sector_t sector;
int op, op_flags = 0, i;
@@ -185,6 +186,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
bio->bi_end_io = nvmet_bio_done;
bio_set_op_attrs(bio, op, op_flags);
+ blk_start_plug(&plug);
for_each_sg(req->sg, sg, req->sg_cnt, i) {
while (bio_add_page(bio, sg_page(sg), sg->length, sg->offset)
!= sg->length) {
@@ -204,6 +206,7 @@ static void nvmet_bdev_execute_rw(struct nvmet_req *req)
}
submit_bio(bio);
+ blk_finish_plug(&plug);
}
static void nvmet_bdev_execute_flush(struct nvmet_req *req)
--
2.16.4