9dea0c81ee
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.