nvme: don't memset() the normal read/write command

This memset in the fast path costs a lot of cycles on my setup. Here's a
top-of-profile of doing ~6.7M IOPS:

+    5.90%  io_uring  [nvme]            [k] nvme_queue_rq
+    5.32%  io_uring  [nvme_core]       [k] nvme_setup_cmd
+    5.17%  io_uring  [kernel.vmlinux]  [k] io_submit_sqes
+    4.97%  io_uring  [kernel.vmlinux]  [k] blkdev_direct_IO

and a perf diff with this patch:

     0.92%     +4.40%  [nvme_core]       [k] nvme_setup_cmd

reducing it from 5.3% to only 0.9%. This takes it from the 2nd most
cycle consumer to something that's mostly irrelevant.

Reviewed-by: Chaitanya Kulkarni <[email protected]>
Reviewed-by: Keith Busch <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

0 files changed, 0 insertions, 0 deletions