engines/io_uring: add support for registered files

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 812440648815d97af8f89b40a20efc35695b967a..6b449e97029b674525983ac158e5b40881f1b733 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -93,6 +93,12 @@ Command line options
                        Dump info related to I/O rate switching.
        *compress*
                        Dump info related to log compress/decompress.
+       *steadystate*
+                       Dump info related to steadystate detection.
+       *helperthread*
+                       Dump info related to the helper thread.
+       *zbd*
+                       Dump info related to support for zoned block devices.
        *?* or *help*
                        Show available debug options.
 
@@ -1246,7 +1252,9 @@ I/O type
        is incremented for each sub-job (i.e. when :option:`numjobs` option is
        specified). This option is useful if there are several jobs which are
        intended to operate on a file in parallel disjoint segments, with even
-       spacing between the starting points.
+       spacing between the starting points. Percentages can be used for this option.
+       If a percentage is given, the generated offset will be aligned to the minimum
+       ``blocksize`` or to the value of ``offset_align`` if provided.
 
 .. option:: number_ios=int
 
@@ -1998,6 +2006,8 @@ I/O engine
                        requests for IME. FIO will then decide when to commit these requests.
                **libiscsi**
                        Read and write iscsi lun with libiscsi.
+               **nbd**
+                       Read and write a Network Block Device (NBD).
 
 I/O engine specific parameters
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -2023,6 +2033,12 @@ with the caveat that when used on the command line, they must come after the
        map and release for each IO. This is more efficient, and reduces the
        IO latency as well.
 
+.. option:: registerfiles : [io_uring]
+       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]
 
        Normally fio will submit IO by issuing a system call to notify the
@@ -2299,6 +2315,15 @@ with the caveat that when used on the command line, they must come after the
        turns on verbose logging from libcurl, 2 additionally enables
        HTTP IO tracing. Default is **0**
 
+.. option:: uri=str : [nbd]
+
+       Specify the NBD URI of the server to test.  The string
+       is a standard NBD URI
+       (see https://github.com/NetworkBlockDevice/nbd/tree/master/doc).
+       Example URIs: nbd://localhost:10809
+       nbd+unix:///?socket=/tmp/socket
+       nbds://tlshost/exportname
+
 I/O depth
 ~~~~~~~~~
 
@@ -2377,7 +2402,7 @@ I/O depth
        this option can reduce both performance and the :option:`iodepth` achieved.
 
        This option only applies to I/Os issued for a single job except when it is
-       enabled along with :option:`io_submit_mode`=offload. In offload mode, fio
+       enabled along with :option:`io_submit_mode`\=offload. In offload mode, fio
        will check for overlap among all I/Os submitted by offload jobs with :option:`serialize_overlap`
        enabled.