defined by \fIioengine\fR. If no \fIioengine\fR is given, list all
available ioengines.
.TP
-.BI \-\-showcmd \fR=\fPjobfile
-Convert \fIjobfile\fR to a set of command\-line options.
+.BI \-\-showcmd
+Convert given \fIjobfile\fRs to a set of command\-line options.
.TP
.BI \-\-readonly
Turn on safety read\-only checks, preventing writes and trims. The \fB\-\-readonly\fR
.RS
.P
.PD 0
-z means Zone
+z means Zone
.P
.PD
.RE
explicit size is specified by \fBfilesize\fR.
.RS
.P
-Each colon in the wanted path must be escaped with a '\\'
+Each colon in the wanted path must be escaped with a '\e'
character. For instance, if the path is `/dev/dsk/foo@3,0:c' then you
would use `filename=/dev/dsk/foo@3,0\\:c' and if the path is
`F:\\filename' then you would use `filename=F\\:\\filename'.
.BI max_open_zones \fR=\fPint
When running a random write test across an entire drive many more zones will be
open than in a typical application workload. Hence this command line option
-that allows to limit the number of open zones. The number of open zones is
+that allows one to limit the number of open zones. The number of open zones is
defined as the number of zones to which write commands are issued by all
threads/processes.
.TP
.TP
.B trimwrite
Sequential trim+write sequences. Blocks will be trimmed first,
-then the same blocks will be written to.
+then the same blocks will be written to. So if `io_size=64K' is specified,
+Fio will trim a total of 64K bytes and also write 64K bytes on the same
+trimmed blocks. This behaviour will be consistent with `number_ios' or
+other Fio options limiting the total bytes or number of I/O's.
+.TP
+.B randtrimwrite
+Like
+.B trimwrite ,
+but uses random offsets rather than sequential writes.
.RE
.P
Fio defaults to read if the option is not specified. For the mixed I/O
effectively caps the file size at `real_size \- offset'. Can be combined with
\fBsize\fR to constrain the start and end range of the I/O workload.
A percentage can be specified by a number between 1 and 100 followed by '%',
-for example, `offset=20%' to specify 20%. In ZBD mode, value can be set as
+for example, `offset=20%' to specify 20%. In ZBD mode, value can be set as
number of zones using 'z'.
.TP
.BI offset_align \fR=\fPint
intended to operate on a file in parallel disjoint segments, with even
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
-\fBblocksize\fR or to the value of \fBoffset_align\fR if provided.In ZBD mode, value
+\fBblocksize\fR or to the value of \fBoffset_align\fR if provided.In ZBD mode, value
can be set as number of zones using 'z'.
.TP
.BI number_ios \fR=\fPint
supplied as a value between 0 and 100.
.P
The second, optional float is allowed for \fBpareto\fR, \fBzipf\fR and \fBnormal\fR
-distributions. It allows to set base of distribution in non-default place, giving
+distributions. It allows one to set base of distribution in non-default place, giving
more control over most probable outcome. This value is in range [0-1] which maps linearly to
range of possible random values.
Defaults are: random for \fBpareto\fR and \fBzipf\fR, and 0.5 for \fBnormal\fR.
files or devices. If the files do not exist, size must be given. It is also
possible to give size as a percentage between 1 and 100. If `size=20%' is
given, fio will use 20% of the full size of the given files or devices. In ZBD mode,
-size can be given in units of number of zones using 'z'. Can be combined with \fBoffset\fR to
+size can be given in units of number of zones using 'z'. Can be combined with \fBoffset\fR to
constrain the start and end range that I/O will be done within.
.TP
.BI io_size \fR=\fPint[%|z] "\fR,\fB io_limit" \fR=\fPint[%|z]
.BI filesize \fR=\fPirange(int)
Individual file sizes. May be a range, in which case fio will select sizes
for files at random within the given range. If not given, each created file
-is the same size. This option overrides \fBsize\fR in terms of file size,
+is the same size. This option overrides \fBsize\fR in terms of file size,
i.e. \fBsize\fR becomes merely the default for \fBio_size\fR (and
has no effect it all if \fBio_size\fR is set explicitly).
.TP
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,io_uring_cmd)nonvectored
+.BI (io_uring,io_uring_cmd)nonvectored \fR=\fPint
With this option, fio will use non-vectored read/write commands, where address
must contain the address directly. Default is -1.
.TP
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.
+the cost of using more CPU in the system. As submission is just the time it
+takes to fill in the sqe entries and any syscall required to wake up the idle
+kernel thread, fio will not report submission latencies.
.TP
-.BI (io_uring,io_uring_cmd)sqthread_poll_cpu
+.BI (io_uring,io_uring_cmd)sqthread_poll_cpu \fR=\fPint
When `sqthread_poll` is set, this option provides a way to define which CPU
should be used for the polling thread.
.TP
When hipri is set this determines the probability of a pvsync2 I/O being high
priority. The default is 100%.
.TP
-.BI (pvsync2,libaio,io_uring)nowait
+.BI (pvsync2,libaio,io_uring,io_uring_cmd)nowait \fR=\fPbool
By default if a request cannot be executed immediately (e.g. resource starvation,
waiting on locks) it is queued and the initiating process will be blocked until
the required resource becomes free.
Specify the label or UUID of the DAOS container to open.
.TP
.BI (dfs)chunk_size
-Specificy a different chunk size (in bytes) for the dfs file.
+Specify a different chunk size (in bytes) for the dfs file.
Use DAOS container's chunk size by default.
.TP
.BI (dfs)object_class
-Specificy a different object class for the dfs file.
+Specify a different object class for the dfs file.
Use DAOS container's object class by default.
.TP
.BI (nfs)nfs_url
.RS
.TP
.B emu
-This is default and used to emulate asynchronous I/O
+This is default and use to emulate asynchronous I/O by using a single thread to
+create a queue pair on top of a synchronous I/O interface using the NVMe driver
+IOCTL.
.TP
.BI thrpool
-Use thread pool for Asynchronous I/O
+Emulate an asynchronous I/O interface with a pool of userspace threads on top
+of a synchronous I/O interface using the NVMe driver IOCTL. By default four
+threads are used.
.TP
.BI io_uring
-Use Linux io_uring/liburing for Asynchronous I/O
+Linux native asynchronous I/O interface which supports both direct and buffered
+I/O.
.TP
.BI libaio
Use Linux aio for Asynchronous I/O
.TP
.BI posix
-Use POSIX aio for Asynchronous I/O
+Use the posix asynchronous I/O interface to perform one or more I/O operations
+asynchronously.
.TP
.BI nil
-Use nil-io; For introspective perf. evaluation
+Do not transfer any data; just pretend to. This is mainly used for
+introspective performance evaluation.
.RE
.RE
.TP
.RS
.TP
.B nvme
-This is default and uses Linux NVMe Driver ioctl() for synchronous I/O
+This is default and uses Linux NVMe Driver ioctl() for synchronous I/O.
.TP
.BI psync
-Use pread()/write() for synchronous I/O
+This supports regular as well as vectored pread() and pwrite() commands.
+.TP
+.BI block
+This is the same as psync except that it also supports zone management
+commands using Linux block layer IOCTLs.
.RE
.RE
.TP
.RS
.TP
.B nvme
-This is default and uses Linux NVMe Driver ioctl() for admin commands
+This is default and uses Linux NVMe Driver ioctl() for admin commands.
.TP
.BI block
-Use Linux Block Layer ioctl() and sysfs for admin commands
-.TP
-.BI file_as_ns
-Use file-stat as to construct NVMe idfy responses
+Use Linux Block Layer ioctl() and sysfs for admin commands.
.RE
.RE
.TP
.BI (xnvme)xnvme_dev_nsid\fR=\fPint
-xnvme namespace identifier, for userspace NVMe driver.
+xnvme namespace identifier for userspace NVMe driver such as SPDK.
.TP
.BI (xnvme)xnvme_iovec
If this option is set, xnvme will use vectored read/write commands.
completed. If this option is used, there are two more stats that are
appended, the total error count and the first error. The error field given
in the stats is the first error that was hit during the run.
+.RS
+.P
+Note: a write error from the device may go unnoticed by fio when using buffered
+IO, as the write() (or similar) system call merely dirties the kernel pages,
+unless `sync' or `direct' is used. Device IO errors occur when the dirty data is
+actually written out to disk. If fully sync writes aren't desirable, `fsync' or
+`fdatasync' can be used as well. This is specific to writes, as reads are always
+synchronous.
+.RS
+.P
The allowed values are:
.RS
.RS
.TP
.B Trace file format v2
The second version of the trace file format was added in fio version 1.17. It
-allows to access more then one file per trace and has a bigger set of possible
+allows one to access more then one file per trace and has a bigger set of possible
file actions.
.RS
.P
projects / fio.git / blobdiff