Spdk/test/nvme/overhead
Jim Harris 488570ebd4 Replace most BSD 3-clause license text with SPDX identifier.
Many open source projects have moved to using SPDX identifiers
to specify license information, reducing the amount of
boilerplate code in every source file.  This patch replaces
the bulk of SPDK .c, .cpp and Makefiles with the BSD-3-Clause
identifier.

Almost all of these files share the exact same license text,
and this patch only modifies the files that contain the
most common license text.  There can be slight variations
because the third clause contains company names - most say
"Intel Corporation", but there are instances for Nvidia,
Samsung, Eideticom and even "the copyright holder".

Used a bash script to automate replacement of the license text
with SPDX identifier which is checked into scripts/spdx.sh.

Signed-off-by: Jim Harris <james.r.harris@intel.com>
Change-Id: Iaa88ab5e92ea471691dc298cfe41ebfb5d169780
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/12904
Community-CI: Broadcom CI <spdk-ci.pdl@broadcom.com>
Community-CI: Mellanox Build Bot
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Aleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Dong Yi <dongx.yi@intel.com>
Reviewed-by: Konrad Sztyber <konrad.sztyber@intel.com>
Reviewed-by: Paul Luse <paul.e.luse@intel.com>
Reviewed-by: <qun.wan@intel.com>
2022-06-09 07:35:12 +00:00
..
.gitignore test: move lib/nvme up one directory 2018-03-27 00:46:52 -04:00
Makefile Replace most BSD 3-clause license text with SPDX identifier. 2022-06-09 07:35:12 +00:00
overhead.c Replace most BSD 3-clause license text with SPDX identifier. 2022-06-09 07:35:12 +00:00
README test: move lib/nvme up one directory 2018-03-27 00:46:52 -04:00

This application measures the software overhead of I/O submission
and completion for both the SPDK NVMe driver and an AIO file handle.
It runs a random read, queue depth = 1 workload to a single device,
and captures TSC as follows:

* Submission: capture TSC before and after the I/O submission
  call (SPDK or AIO).
* Completion: capture TSC before and after the I/O completion
  check.  Only record the TSC delta if the I/O completion check
  resulted in a completed I/O.  Also use heuristics in the AIO
  case to account for time spent in interrupt handling outside
  of the actual I/O completion check.

Usage:

To test software overhead for a 4KB I/O over a 10 second period:

SPDK:  overhead -s 4096 -t 10
AIO:   overhead -s 4096 -t 10 /dev/nvme0n1

Note that for the SPDK case, it will only use the first namespace
on the first controller found by SPDK.  If a different namespace is
desired, attach controllers individually to the kernel NVMe driver
to ensure they will not be enumerated by SPDK.