[PATCH v3 6/9] docs: document options for io_uring_cmd I/O engine

From: Ankit Kumar <ankit.kumar@samsung.com>
To: axboe@kernel.dk
Cc: fio@vger.kernel.org, krish.reddy@samsung.com,
	joshi.k@samsung.com, anuj20.g@samsung.com,
	Ankit Kumar <ankit.kumar@samsung.com>
Subject: [PATCH v3 6/9] docs: document options for io_uring_cmd I/O engine
Date: Tue, 31 May 2022 19:01:52 +0530	[thread overview]
Message-ID: <20220531133155.17493-7-ankit.kumar@samsung.com> (raw)
In-Reply-To: <20220531133155.17493-1-ankit.kumar@samsung.com>

Update documentation with io_uring_cmd I/O engine specific options.
Add missing io_uring I/O engine entry from fio man page.
Update docs with missing io_uring engine specific options.

Signed-off-by: Ankit Kumar <ankit.kumar@samsung.com>
---
 HOWTO.rst | 41 +++++++++++++++++++++++++++++++----------
 fio.1     | 33 ++++++++++++++++++++++++++++-----
 2 files changed, 59 insertions(+), 15 deletions(-)

diff --git a/HOWTO.rst b/HOWTO.rst
index 8ab3ac4b..28ac2b7c 100644
--- a/HOWTO.rst
+++ b/HOWTO.rst
@@ -1952,6 +1952,10 @@ I/O engine
 			for both direct and buffered IO.
 			This engine defines engine specific options.
 
+		**io_uring_cmd**
+			Fast Linux native asynchronous I/O for pass through commands.
+			This engine defines engine specific options.
+
 		**libaio**
 			Linux native asynchronous I/O. Note that Linux may only support
 			queued behavior with non-buffered I/O (set ``direct=1`` or
@@ -2255,22 +2259,34 @@ with the caveat that when used on the command line, they must come after the
 	values for trim IOs are ignored. This option is mutually exclusive with
 	the :option:`cmdprio_percentage` option.
 
-.. option:: fixedbufs : [io_uring]
+.. option:: fixedbufs : [io_uring] [io_uring_cmd]
+
+	If fio is asked to do direct IO, then Linux will map pages for each
+	IO call, and release them when IO is done. If this option is set, the
+	pages are pre-mapped before IO is started. This eliminates the need to
+	map and release for each IO. This is more efficient, and reduces the
+	IO latency as well.
+
+.. option:: nonvectored : [io_uring] [io_uring_cmd]
 
-    If fio is asked to do direct IO, then Linux will map pages for each
-    IO call, and release them when IO is done. If this option is set, the
-    pages are pre-mapped before IO is started. This eliminates the need to
-    map and release for each IO. This is more efficient, and reduces the
-    IO latency as well.
+	With this option, fio will use non-vectored read/write commands, where
+	address must contain the address directly. Default is -1.
 
-.. option:: registerfiles : [io_uring]
+.. option:: force_async=int : [io_uring] [io_uring_cmd]
+
+	Normal operation for io_uring is to try and issue an sqe as
+	non-blocking first, and if that fails, execute it in an async manner.
+	With this option set to N, then every N request fio will ask sqe to
+	be issued in an async manner. Default is 0.
+
+.. option:: registerfiles : [io_uring] [io_uring_cmd]
 
 	With this option, fio registers the set of files being used with the
 	kernel. This avoids the overhead of managing file counts in the kernel,
 	making the submission and completion part more lightweight. Required
 	for the below :option:`sqthread_poll` option.
 
-.. option:: sqthread_poll : [io_uring] [xnvme]
+.. option:: sqthread_poll : [io_uring] [io_uring_cmd] [xnvme]
 
 	Normally fio will submit IO by issuing a system call to notify the
 	kernel of available items in the SQ ring. If this option is set, the
@@ -2278,14 +2294,19 @@ with the caveat that when used on the command line, they must come after the
 	This frees up cycles for fio, at the cost of using more CPU in the
 	system.
 
-.. option:: sqthread_poll_cpu : [io_uring]
+.. option:: sqthread_poll_cpu : [io_uring] [io_uring_cmd]
 
 	When :option:`sqthread_poll` is set, this option provides a way to
 	define which CPU should be used for the polling thread.
 
+.. option:: cmd_type=str : [io_uring_cmd]
+
+	Specifies the type of uring passthrough command to be used. Supported
+	value is nvme. Default is nvme.
+
 .. option:: hipri
 
-   [io_uring], [xnvme]
+   [io_uring] [io_uring_cmd] [xnvme]
 
         If this option is set, fio will attempt to use polled IO completions.
         Normal IO completions generate interrupts to signal the completion of
diff --git a/fio.1 b/fio.1
index bdba3142..948c01f9 100644
--- a/fio.1
+++ b/fio.1
@@ -1739,6 +1739,15 @@ Basic \fBpreadv\fR\|(2) or \fBpwritev\fR\|(2) I/O.
 .B pvsync2
 Basic \fBpreadv2\fR\|(2) or \fBpwritev2\fR\|(2) I/O.
 .TP
+.B io_uring
+Fast Linux native asynchronous I/O. Supports async IO
+for both direct and buffered IO.
+This engine defines engine specific options.
+.TP
+.B io_uring_cmd
+Fast Linux native asynchronous I/O for passthrough commands.
+This engine defines engine specific options.
+.TP
 .B libaio
 Linux native asynchronous I/O. Note that Linux may only support
 queued behavior with non-buffered I/O (set `direct=1' or
@@ -2040,35 +2049,49 @@ for trim IOs are ignored. This option is mutually exclusive with the
 \fBcmdprio_percentage\fR option.
 .RE
 .TP
-.BI (io_uring)fixedbufs
+.BI (io_uring,io_uring_cmd)fixedbufs
 If fio is asked to do direct IO, then Linux will map pages for each IO call, and
 release them when IO is done. If this option is set, the pages are pre-mapped
 before IO is started. This eliminates the need to map and release for each IO.
 This is more efficient, and reduces the IO latency as well.
 .TP
-.BI (io_uring,xnvme)hipri
+.BI (io_uring,io_uring_cmd)nonvectored
+With this option, fio will use non-vectored read/write commands, where address
+must contain the address directly. Default is -1.
+.TP
+.BI (io_uring,io_uring_cmd)force_async
+Normal operation for io_uring is to try and issue an sqe as non-blocking first,
+and if that fails, execute it in an async manner. With this option set to N,
+then every N request fio will ask sqe to be issued in an async manner. Default
+is 0.
+.TP
+.BI (io_uring,io_uring_cmd,xnvme)hipri
 If this option is set, fio will attempt to use polled IO completions. Normal IO
 completions generate interrupts to signal the completion of IO, polled
 completions do not. Hence they are require active reaping by the application.
 The benefits are more efficient IO for high IOPS scenarios, and lower latencies
 for low queue depth IO.
 .TP
-.BI (io_uring)registerfiles
+.BI (io_uring,io_uring_cmd)registerfiles
 With this option, fio registers the set of files being used with the kernel.
 This avoids the overhead of managing file counts in the kernel, making the
 submission and completion part more lightweight. Required for the below
 sqthread_poll option.
 .TP
-.BI (io_uring,xnvme)sqthread_poll
+.BI (io_uring,io_uring_cmd,xnvme)sqthread_poll
 Normally fio will submit IO by issuing a system call to notify the kernel of
 available items in the SQ ring. If this option is set, the act of submitting IO
 will be done by a polling thread in the kernel. This frees up cycles for fio, at
 the cost of using more CPU in the system.
 .TP
-.BI (io_uring)sqthread_poll_cpu
+.BI (io_uring,io_uring_cmd)sqthread_poll_cpu
 When `sqthread_poll` is set, this option provides a way to define which CPU
 should be used for the polling thread.
 .TP
+.BI (io_uring_cmd)cmd_type \fR=\fPstr
+Specifies the type of uring passthrough command to be used. Supported
+value is nvme. Default is nvme.
+.TP
 .BI (libaio)userspace_reap
 Normally, with the libaio engine in use, fio will use the
 \fBio_getevents\fR\|(3) system call to reap newly returned events. With
-- 
2.17.1

