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>
9dea0c81ee