From 9dea0c81ee4a7b5d8e5bc0d4cfa2ee4f0e7b13f0 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 28 Oct 2019 11:23:26 -0700 Subject: nvmet: add plugging for read/write when ns is bdev MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Christoph Hellwig Signed-off-by: Chaitanya Kulkarni Signed-off-by: Keith Busch Signed-off-by: Jens Axboe --- drivers/nvme/target/io-cmd-bdev.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'drivers') 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) -- cgit