.BI \-\-parse\-only
Parse options only, don't start any I/O.
.TP
+.BI \-\-merge\-blktrace\-only
+Merge blktraces only, don't start any I/O.
+.TP
.BI \-\-output \fR=\fPfilename
Write output to \fIfilename\fR.
.TP
Convert \fIjobfile\fR to a set of command\-line options.
.TP
.BI \-\-readonly
-Turn on safety read\-only checks, preventing writes. The \fB\-\-readonly\fR
+Turn on safety read\-only checks, preventing writes and trims. The \fB\-\-readonly\fR
option is an extra safety guard to prevent users from accidentally starting
-a write workload when that is not desired. Fio will only write if
-`rw=write/randwrite/rw/randrw' is given. This extra safety net can be used
-as an extra precaution as \fB\-\-readonly\fR will also enable a write check in
-the I/O engine core to prevent writes due to unknown user space bug(s).
+a write or trim workload when that is not desired. Fio will only modify the
+device under test if `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite'
+is given. This safety net can be used as an extra precaution.
.TP
.BI \-\-eta \fR=\fPwhen
Specifies when real\-time ETA estimate should be printed. \fIwhen\fR may
Force a full status dump of cumulative (from job start) values at \fItime\fR
intervals. This option does *not* provide per-period measurements. So
values such as bandwidth are running averages. When the time unit is omitted,
-\fItime\fR is interpreted in seconds.
+\fItime\fR is interpreted in seconds. Note that using this option with
+`\-\-output-format=json' will yield output that technically isn't valid json,
+since the output will be collated sets of valid json. It will need to be split
+into valid sets of json after the run.
.TP
.BI \-\-section \fR=\fPname
Only run specified section \fIname\fR in job file. Multiple sections can be specified.
parsed and used.
.TP
.BI \-\-alloc\-size \fR=\fPkb
-Set the internal smalloc pool size to \fIkb\fR in KiB. The
-\fB\-\-alloc\-size\fR switch allows one to use a larger pool size for smalloc.
+Allocate additional internal smalloc pools of size \fIkb\fR in KiB. The
+\fB\-\-alloc\-size\fR option increases shared memory set aside for use by fio.
If running large jobs with randommap enabled, fio can run out of memory.
Smalloc is an internal allocator for shared structures from a fixed size
memory pool and can grow to 16 pools. The pool size defaults to 16MiB.
Set this \fIcommand\fR as remote trigger.
.TP
.BI \-\-aux\-path \fR=\fPpath
-Use this \fIpath\fR for fio state generated files.
+Use the directory specified by \fIpath\fP for generated state files instead
+of the current working directory.
.SH "JOB FILE FORMAT"
Any parameters following the options will be assumed to be job files, unless
they match a job file parameter. Multiple job files can be listed and each job
See the `examples/' directory for inspiration on how to write job files. Note
the copyright and license requirements currently apply to
`examples/' files.
+
+Note that the maximum length of a line in the job file is 8192 bytes.
.SH "JOB FILE PARAMETERS"
Some parameters take an option of a given type, such as an integer or a
string. Anywhere a numeric value is required, an arithmetic expression may be
unless otherwise specified.
.P
With `kb_base=1000', fio follows international standards for unit
-prefixes. To specify power\-of\-10 decimal values defined in the
+prefixes. To specify power-of-10 decimal values defined in the
International System of Units (SI):
.RS
.P
.PD
.RE
.P
-To specify power\-of\-2 binary values defined in IEC 80000\-13:
+To specify power-of-2 binary values defined in IEC 80000-13:
.RS
.P
.PD 0
.RE
.P
With `kb_base=1024' (the default), the unit prefixes are opposite
-from those specified in the SI and IEC 80000\-13 standards to provide
+from those specified in the SI and IEC 80000-13 standards to provide
compatibility with old scripts. For example, 4k means 4096.
.P
For quantities of data, an optional unit of 'B' may be included
.RS
.TP
.B 1000
-Inputs comply with IEC 80000\-13 and the International
+Inputs comply with IEC 80000-13 and the International
System of Units (SI). Use:
.RS
.P
.PD 0
-\- power\-of\-2 values with IEC prefixes (e.g., KiB)
+\- power-of-2 values with IEC prefixes (e.g., KiB)
.P
-\- power\-of\-10 values with SI prefixes (e.g., kB)
+\- power-of-10 values with SI prefixes (e.g., kB)
.PD
.RE
.TP
.P
.RS
.PD 0
-\- power\-of\-2 values with SI prefixes
+\- power-of-2 values with SI prefixes
.P
-\- power\-of\-10 values with IEC prefixes
+\- power-of-10 values with IEC prefixes
.PD
.RE
.RE
See \fBbs\fR for more details on input parameters.
.P
Outputs always use correct prefixes. Most outputs include both
-side\-by\-side, like:
+side-by-side, like:
.P
.RS
bw=2383.3kB/s (2327.4KiB/s)
.RS
.TP
.B 0
-Use auto\-detection (default).
+Use auto-detection (default).
.TP
.B 8
Byte based.
assigned equally distributed to job clones created by \fBnumjobs\fR as
long as they are using generated filenames. If specific \fBfilename\fR(s) are
set fio will use the first listed directory, and thereby matching the
-\fBfilename\fR semantic which generates a file each clone if not specified, but
-let all clones use the same if set.
+\fBfilename\fR semantic (which generates a file for each clone if not
+specified, but lets all clones use the same file if set).
.RS
.P
-See the \fBfilename\fR option for information on how to escape ':' and '\'
+See the \fBfilename\fR option for information on how to escape ':'
characters within the directory path itself.
+.P
+Note: To control the directory fio will use for internal state files
+use \fB\-\-aux\-path\fR.
.RE
.TP
.BI filename \fR=\fPstr
explicit size is specified by \fBfilesize\fR.
.RS
.P
-Each colon and backslash in the wanted path must be escaped with a '\'
+Each colon in the wanted path must be escaped with a '\\'
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'.
+`F:\\filename' then you would use `filename=F\\:\\filename'.
.P
-On Windows, disk devices are accessed as `\\\\\\\\.\\\\PhysicalDrive0' for
-the first device, `\\\\\\\\.\\\\PhysicalDrive1' for the second etc.
+On Windows, disk devices are accessed as `\\\\.\\PhysicalDrive0' for
+the first device, `\\\\.\\PhysicalDrive1' for the second etc.
Note: Windows and FreeBSD prevent write access to areas
-of the disk containing in\-use data (e.g. filesystems).
+of the disk containing in-use data (e.g. filesystems).
.P
The filename `\-' is a reserved name, meaning *stdin* or *stdout*. Which
of the two depends on the read/write direction set.
For \fBrandom\fR, \fBroundrobin\fR, and \fBsequential\fR, a postfix can be appended to
tell fio how many I/Os to issue before switching to a new file. For example,
specifying `file_service_type=random:8' would cause fio to issue
-8 I/Os before selecting a new file at random. For the non\-uniform
+8 I/Os before selecting a new file at random. For the non-uniform
distributions, a floating point postfix can be given to influence how the
distribution is skewed. See \fBrandom_distribution\fR for a description
of how that would work.
\fBfsync\fR\|(2) the data file after creation. This is the default.
.TP
.BI create_on_open \fR=\fPbool
-If true, don't pre\-create files but allow the job's open() to create a file
-when it's time to do I/O. Default: false \-\- pre\-create all necessary files
+If true, don't pre-create files but allow the job's open() to create a file
+when it's time to do I/O. Default: false \-\- pre-create all necessary files
when the job starts.
.TP
.BI create_only \fR=\fPbool
writing against a mounted device regardless of this option. Default: false.
.TP
.BI pre_read \fR=\fPbool
-If this is given, files will be pre\-read into memory before starting the
+If this is given, files will be pre-read into memory before starting the
given I/O operation. This will also clear the \fBinvalidate\fR flag,
-since it is pointless to pre\-read and then drop the cache. This will only
-work for I/O engines that are seek\-able, since they allow you to read the
-same data multiple times. Thus it will not work on non\-seekable I/O engines
+since it is pointless to pre-read and then drop the cache. This will only
+work for I/O engines that are seek-able, since they allow you to read the
+same data multiple times. Thus it will not work on non-seekable I/O engines
(e.g. network, splice). Default: false.
.TP
.BI unlink \fR=\fPbool
.BI unlink_each_loop \fR=\fPbool
Unlink job files after each iteration or loop. Default: false.
.TP
-.BI zonesize \fR=\fPint
-Divide a file into zones of the specified size. See \fBzoneskip\fR.
+.BI zonemode \fR=\fPstr
+Accepted values are:
+.RS
+.RS
+.TP
+.B none
+The \fBzonerange\fR, \fBzonesize\fR and \fBzoneskip\fR parameters are ignored.
+.TP
+.B strided
+I/O happens in a single zone until \fBzonesize\fR bytes have been transferred.
+After that number of bytes has been transferred processing of the next zone
+starts.
+.TP
+.B zbd
+Zoned block device mode. I/O happens sequentially in each zone, even if random
+I/O has been selected. Random I/O happens across all zones instead of being
+restricted to a single zone.
+.RE
+.RE
.TP
.BI zonerange \fR=\fPint
-Give size of an I/O zone. See \fBzoneskip\fR.
+For \fBzonemode\fR=strided, this is the size of a single zone. See also
+\fBzonesize\fR and \fBzoneskip\fR.
+
+For \fBzonemode\fR=zbd, this parameter is ignored.
+.TP
+.BI zonesize \fR=\fPint
+For \fBzonemode\fR=strided, this is the number of bytes to transfer before
+skipping \fBzoneskip\fR bytes. If this parameter is smaller than
+\fBzonerange\fR then only a fraction of each zone with \fBzonerange\fR bytes
+will be accessed. If this parameter is larger than \fBzonerange\fR then each
+zone will be accessed multiple times before skipping to the next zone.
+
+For \fBzonemode\fR=zbd, this is the size of a single zone. The
+\fBzonerange\fR parameter is ignored in this mode. For a job accessing a
+zoned block device, the specified \fBzonesize\fR must be 0 or equal to the
+device zone size. For a regular block device or file, the specified
+\fBzonesize\fR must be at least 512B.
.TP
.BI zoneskip \fR=\fPint
-Skip the specified number of bytes when \fBzonesize\fR data has been
-read. The two zone options can be used to only do I/O on zones of a file.
+For \fBzonemode\fR=strided, the number of bytes to skip after \fBzonesize\fR
+bytes of data have been transferred.
+
+For \fBzonemode\fR=zbd, the \fBzonesize\fR aligned number of bytes to skip
+once a zone is fully written (write workloads) or all written data in the
+zone have been read (read workloads). This parameter is valid only for
+sequential workloads and ignored for random workloads. For read workloads,
+see also \fBread_beyond_wp\fR.
+
+.TP
+.BI read_beyond_wp \fR=\fPbool
+This parameter applies to \fBzonemode=zbd\fR only.
+
+Zoned block devices are block devices that consist of multiple zones. Each
+zone has a type, e.g. conventional or sequential. A conventional zone can be
+written at any offset that is a multiple of the block size. Sequential zones
+must be written sequentially. The position at which a write must occur is
+called the write pointer. A zoned block device can be either host managed or
+host aware. For host managed devices the host must ensure that writes happen
+sequentially. Fio recognizes host managed devices and serializes writes to
+sequential zones for these devices.
+
+If a read occurs in a sequential zone beyond the write pointer then the zoned
+block device will complete the read without reading any data from the storage
+medium. Since such reads lead to unrealistically high bandwidth and IOPS
+numbers fio only reads beyond the write pointer if explicitly told to do
+so. Default: false.
+.TP
+.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
+defined as the number of zones to which write commands are issued by all
+threads/processes.
+.TP
+.BI job_max_open_zones \fR=\fPint
+Limit on the number of simultaneously opened zones per single thread/process.
+.TP
+.BI zone_reset_threshold \fR=\fPfloat
+A number between zero and one that indicates the ratio of logical blocks with
+data to the total number of logical blocks in the test above which zones
+should be reset periodically.
+.TP
+.BI zone_reset_frequency \fR=\fPfloat
+A number between zero and one that indicates how often a zone reset should be
+issued if the zone reset threshold has been exceeded. A zone reset is
+submitted after each (1 / zone_reset_frequency) write requests. This and the
+previous parameter can be used to simulate garbage collection activity.
+
.SS "I/O type"
.TP
.BI direct \fR=\fPbool
-If value is true, use non\-buffered I/O. This is usually O_DIRECT. Note that
+If value is true, use non-buffered I/O. This is usually O_DIRECT. Note that
OpenBSD and ZFS on Solaris don't support direct I/O. On Windows the synchronous
ioengines don't support direct I/O. Default: false.
.TP
Sequential writes.
.TP
.B trim
-Sequential trims (Linux block devices only).
+Sequential trims (Linux block devices and SCSI character devices only).
.TP
.B randread
Random reads.
Random writes.
.TP
.B randtrim
-Random trims (Linux block devices only).
+Random trims (Linux block devices and SCSI character devices only).
.TP
.B rw,readwrite
Sequential mixed reads and writes.
sequence depends on the \fBrandrepeat\fR setting.
.TP
.BI fallocate \fR=\fPstr
-Whether pre\-allocation is performed when laying down files.
+Whether pre-allocation is performed when laying down files.
Accepted values are:
.RS
.RS
.TP
.B none
-Do not pre\-allocate space.
+Do not pre-allocate space.
.TP
.B native
-Use a platform's native pre\-allocation call but fall back to
+Use a platform's native pre-allocation call but fall back to
\fBnone\fR behavior if it fails/is not implemented.
.TP
.B posix
-Pre\-allocate via \fBposix_fallocate\fR\|(3).
+Pre-allocate via \fBposix_fallocate\fR\|(3).
.TP
.B keep
-Pre\-allocate via \fBfallocate\fR\|(2) with
+Pre-allocate via \fBfallocate\fR\|(2) with
FALLOC_FL_KEEP_SIZE set.
.TP
+.B truncate
+Extend file to final size using \fBftruncate\fR|(2)
+instead of allocating.
+.TP
.B 0
-Backward\-compatible alias for \fBnone\fR.
+Backward-compatible alias for \fBnone\fR.
.TP
.B 1
-Backward\-compatible alias for \fBposix\fR.
+Backward-compatible alias for \fBposix\fR.
.RE
.P
May not be available on all supported platforms. \fBkeep\fR is only available
on Linux. If using ZFS on Solaris this cannot be set to \fBposix\fR
-because ZFS doesn't support pre\-allocation. Default: \fBnative\fR if any
-pre\-allocation methods are available, \fBnone\fR if not.
+because ZFS doesn't support pre-allocation. Default: \fBnative\fR if any
+pre-allocation methods except \fBtruncate\fR are available, \fBnone\fR if not.
+.P
+Note that using \fBtruncate\fR on Windows will interact surprisingly
+with non-sequential write patterns. When writing to a file that has
+been extended by setting the end-of-file information, Windows will
+backfill the unwritten portion of the file up to that offset with
+zeroes before issuing the new write. This means that a single small
+write to the end of an extended file will stall until the entire
+file has been filled with zeroes.
.RE
.TP
.BI fadvise_hint \fR=\fPstr
.BI offset_increment \fR=\fPint
If this is provided, then the real offset becomes `\fBoffset\fR + \fBoffset_increment\fR
* thread_number', where the thread number is a counter that starts at 0 and
-is incremented for each sub\-job (i.e. when \fBnumjobs\fR option is
+is incremented for each sub-job (i.e. when \fBnumjobs\fR 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
+\fBblocksize\fR or to the value of \fBoffset_align\fR if provided.
.TP
.BI number_ios \fR=\fPint
Fio will normally perform I/Os until it has exhausted the size of the region
the number of I/Os to perform. When fio reaches this number, it will exit
normally and report status. Note that this does not extend the amount of I/O
that will be done, it will only stop fio if this condition is met before
-other end\-of\-job criteria.
+other end-of-job criteria.
.TP
.BI fsync \fR=\fPint
If writing to a file, issue an \fBfsync\fR\|(2) (or its equivalent) of
the dirty data for every number of blocks given. For example, if you give 32
as a parameter, fio will sync the file after every 32 writes issued. If fio is
-using non\-buffered I/O, we may not sync the file. The exception is the sg
+using non-buffered I/O, we may not sync the file. The exception is the sg
I/O engine, which synchronizes the disk cache anyway. Defaults to 0, which
means fio does not periodically issue and wait for a sync to complete. Also
see \fBend_fsync\fR and \fBfsync_on_close\fR.
.TP
.BI fdatasync \fR=\fPint
Like \fBfsync\fR but uses \fBfdatasync\fR\|(2) to only sync data and
-not metadata blocks. In Windows, FreeBSD, and DragonFlyBSD there is no
+not metadata blocks. In Windows, FreeBSD, DragonFlyBSD or OSX there is no
\fBfdatasync\fR\|(2) so this falls back to using \fBfsync\fR\|(2).
Defaults to 0, which means fio does not periodically issue and wait for a
-data\-only sync to complete.
+data-only sync to complete.
.TP
.BI write_barrier \fR=\fPint
Make every N\-th write a barrier write.
defaults to 100%, in which case the workload is fully random. It can be set
from anywhere from 0 to 100. Setting it to 0 would make the workload fully
sequential. Any setting in between will result in a random mix of sequential
-and random I/O, at the given percentages. Comma\-separated values may be
+and random I/O, at the given percentages. Comma-separated values may be
specified for reads, writes, and trims as described in \fBblocksize\fR.
.TP
.BI norandommap
at past I/O history. This means that some blocks may not be read or written,
and that some blocks may be read/written more than once. If this option is
used with \fBverify\fR and multiple blocksizes (via \fBbsrange\fR),
-only intact blocks are verified, i.e., partially\-overwritten blocks are
-ignored.
+only intact blocks are verified, i.e., partially-overwritten blocks are
+ignored. With an async I/O engine and an I/O depth > 1, it is possible for
+the same block to be overwritten, which can cause verification errors. Either
+do not use norandommap in this case, or also use the lfsr random generator.
.TP
.BI softrandommap \fR=\fPbool
See \fBnorandommap\fR. If fio runs with the random block map enabled and
.TP
.BI blocksize \fR=\fPint[,int][,int] "\fR,\fB bs" \fR=\fPint[,int][,int]
The block size in bytes used for I/O units. Default: 4096. A single value
-applies to reads, writes, and trims. Comma\-separated values may be
+applies to reads, writes, and trims. Comma-separated values may be
specified for reads, writes, and trims. A value not terminated in a comma
applies to subsequent types. Examples:
.RS
A range of block sizes in bytes for I/O units. The issued I/O unit will
always be a multiple of the minimum size, unless
\fBblocksize_unaligned\fR is set.
-Comma\-separated ranges may be specified for reads, writes, and trims as
+Comma-separated ranges may be specified for reads, writes, and trims as
described in \fBblocksize\fR. Example:
.RS
.RS
would have 50% 4k ios, and 25% 1k and 32k ios. The percentages always add up
to 100, if bssplit is given a range that adds up to more, it will error out.
.P
-Comma\-separated values may be specified for reads, writes, and trims as
+Comma-separated values may be specified for reads, writes, and trims as
described in \fBblocksize\fR.
.P
If you want a workload that has 50% 2k reads and 50% 4k reads, while having
90% 4k writes and 10% 8k writes, you would specify:
.RS
.P
-bssplit=2k/50:4k/50,4k/90,8k/10
+bssplit=2k/50:4k/50,4k/90:8k/10
.RE
.P
Fio supports defining up to 64 different weights for each data direction.
\fBblocksize\fR. Minimum alignment is typically 512b for using direct
I/O, though it usually depends on the hardware block size. This option is
mutually exclusive with using a random map for files, so it will turn off
-that option. Comma\-separated values may be specified for reads, writes, and
+that option. Comma-separated values may be specified for reads, writes, and
trims as described in \fBblocksize\fR.
.SS "Buffers and memory"
.TP
.BI scramble_buffers \fR=\fPbool
If \fBrefill_buffers\fR is too costly and the target is using data
deduplication, then setting this option will slightly modify the I/O buffer
-contents to defeat normal de\-dupe attempts. This is not enough to defeat
+contents to defeat normal de-dupe attempts. This is not enough to defeat
more clever block compression attempts, but it will stop naive dedupe of
blocks. Default: true.
.TP
given job file, add up the I/O depth of all jobs (normally one unless
\fBiodepth\fR is used) and multiply by the maximum bs set. Then divide
that number by the huge page size. You can see the size of the huge pages in
-`/proc/meminfo'. If no huge pages are allocated by having a non\-zero
+`/proc/meminfo'. If no huge pages are allocated by having a non-zero
number in `nr_hugepages', using \fBmmaphuge\fR or \fBshmhuge\fR will fail. Also
see \fBhugepage\-size\fR.
.P
Defines the size of a huge page. Must at least be equal to the system
setting, see `/proc/meminfo'. Defaults to 4MiB. Should probably
always be a multiple of megabytes, so using `hugepage\-size=Xm' is the
-preferred way to set this to avoid setting a non\-pow\-2 bad value.
+preferred way to set this to avoid setting a non-pow-2 bad value.
.TP
.BI lockmem \fR=\fPint
Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to
Perform I/O after the end of the file. Normally fio will operate within the
size of a file. If this option is set, then fio will append to the file
instead. This has identical behavior to setting \fBoffset\fR to the size
-of a file. This option is ignored on non\-regular files.
+of a file. This option is ignored on non-regular files.
.TP
.BI fill_device \fR=\fPbool "\fR,\fB fill_fs" \fR=\fPbool
Sets size to something really large and waits for ENOSPC (no space left on
write. For a read workload, the mount point will be filled first then I/O
started on the result. This option doesn't make sense if operating on a raw
device node, since the size of that is already known by the file system.
-Additionally, writing beyond end\-of\-device will not return ENOSPC there.
+Additionally, writing beyond end-of-device will not return ENOSPC there.
.SS "I/O engine"
.TP
.BI ioengine \fR=\fPstr
.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
+queued behavior with non-buffered I/O (set `direct=1' or
`buffered=0').
This engine defines engine specific options.
.TP
ioctl, or if the target is an sg character device we use
\fBread\fR\|(2) and \fBwrite\fR\|(2) for asynchronous
I/O. Requires \fBfilename\fR option to specify either block or
-character devices. The sg engine includes engine specific options.
+character devices. This engine supports trim operations. The
+sg engine includes engine specific options.
+.TP
+.B libzbc
+Synchronous I/O engine for SMR hard-disks using the \fBlibzbc\fR
+library. The target can be either an sg character device or
+a block device file. This engine supports the zonemode=zbd zone
+operations.
.TP
.B null
Doesn't transfer any data, just pretends to. This is mainly used to
of the CPU. In case of SMP machines, use `numjobs=<nr_of_cpu>'
to get desired CPU usage, as the cpuload only loads a
single CPU at the desired rate. A job never finishes unless there is
-at least one non\-cpuio job.
+at least one non-cpuio job.
.TP
.B guasi
The GUASI I/O engine is the Generic Userspace Asynchronous Syscall
-Interface approach to async I/O. See \fIhttp://www.xmailserver.org/guasi\-lib.html\fR
+Interface approach to async I/O. See \fIhttp://www.xmailserver.org/guasi-lib.html\fR
for more info on GUASI.
.TP
.B rdma
(RBD) via librbd without the need to use the kernel rbd driver. This
ioengine defines engine specific options.
.TP
+.B http
+I/O engine supporting GET/PUT requests over HTTP(S) with libcurl to
+a WebDAV or S3 endpoint. This ioengine defines engine specific options.
+
+This engine only supports direct IO of iodepth=1; you need to scale this
+via numjobs. blocksize defines the size of the objects to be created.
+
+TRIM is translated to object deletion.
+.TP
.B gfapi
Using GlusterFS libgfapi sync interface to direct access to
GlusterFS volumes without having to go through FUSE. This ioengine
\fBfilesize\fR so that all the accounting still occurs, but no actual I/O will be
done other than creating the file.
.TP
+.B filestat
+Simply do stat() and do no I/O to the file. You need to set 'filesize'
+and 'nrfiles', so that files will be created.
+This engine is to measure file lookup and meta data access.
+.TP
.B libpmem
Read and write using mmap I/O to a file on a filesystem
mounted with DAX on a persistent memory device through the PMDK
libpmem library.
+.TP
+.B ime_psync
+Synchronous read and write using DDN's Infinite Memory Engine (IME). This
+engine is very basic and issues calls to IME whenever an IO is queued.
+.TP
+.B ime_psyncv
+Synchronous read and write using DDN's Infinite Memory Engine (IME). This
+engine uses iovecs and will try to stack as much IOs as possible (if the IOs
+are "contiguous" and the IO depth is not exceeded) before issuing a call to IME.
+.TP
+.B ime_aio
+Asynchronous read and write using DDN's Infinite Memory Engine (IME). This
+engine will try to stack as much IOs as possible by creating requests for IME.
+FIO will then decide when to commit these requests.
+.TP
+.B libiscsi
+Read and write iscsi lun with libiscsi.
+.TP
+.B nbd
+Synchronous read and write a Network Block Device (NBD).
.SS "I/O engine specific parameters"
In addition, there are some parameters which are only valid when a specific
\fBioengine\fR is in use. These are used identically to normal parameters,
with the caveat that when used on the command line, they must come after the
\fBioengine\fR that defines them is selected.
.TP
+.BI (io_uring, libaio)cmdprio_percentage \fR=\fPint
+Set the percentage of I/O that will be issued with higher priority by setting
+the priority bit. Non-read I/O is likely unaffected by ``cmdprio_percentage``.
+This option cannot be used with the `prio` or `prioclass` options. For this
+option to set the priority bit properly, NCQ priority must be supported and
+enabled and `direct=1' option must be used. fio must also be run as the root
+user.
+.TP
+.BI (io_uring)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)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
+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)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
+When `sqthread_poll` is set, this option provides a way to define which CPU
+should be used for the polling thread.
+.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
-this flag turned on, the AIO ring will be read directly from user\-space to
+this flag turned on, the AIO ring will be read directly from user-space to
reap events. The reaping mode is only enabled when polling for a minimum of
0 events (e.g. when `iodepth_batch_complete=0').
.TP
Poll store instead of waiting for completion. Usually this provides better
throughput at cost of higher(up to 100%) CPU utilization.
.TP
+.BI (http)http_host \fR=\fPstr
+Hostname to connect to. For S3, this could be the bucket name. Default
+is \fBlocalhost\fR
+.TP
+.BI (http)http_user \fR=\fPstr
+Username for HTTP authentication.
+.TP
+.BI (http)http_pass \fR=\fPstr
+Password for HTTP authentication.
+.TP
+.BI (http)https \fR=\fPstr
+Whether to use HTTPS instead of plain HTTP. \fRon\fP enables HTTPS;
+\fRinsecure\fP will enable HTTPS, but disable SSL peer verification (use
+with caution!). Default is \fBoff\fR.
+.TP
+.BI (http)http_mode \fR=\fPstr
+Which HTTP access mode to use: webdav, swift, or s3. Default is
+\fBwebdav\fR.
+.TP
+.BI (http)http_s3_region \fR=\fPstr
+The S3 region/zone to include in the request. Default is \fBus-east-1\fR.
+.TP
+.BI (http)http_s3_key \fR=\fPstr
+The S3 secret key.
+.TP
+.BI (http)http_s3_keyid \fR=\fPstr
+The S3 key/access id.
+.TP
+.BI (http)http_swift_auth_token \fR=\fPstr
+The Swift auth token. See the example configuration file on how to
+retrieve this.
+.TP
+.BI (http)http_verbose \fR=\fPint
+Enable verbose requests from libcurl. Useful for debugging. 1 turns on
+verbose logging from libcurl, 2 additionally enables HTTP IO tracing.
+Default is \fB0\fR
+.TP
.BI (mtd)skip_bad \fR=\fPbool
Skip operations against known bad blocks.
.TP
function. This can be useful when multiple paths exist between the
client and the server or in certain loopback configurations.
.TP
+.BI (filestat)stat_type \fR=\fPstr
+Specify stat system call type to measure lookup/getattr performance.
+Default is \fBstat\fR for \fBstat\fR\|(2).
+.TP
.BI (sg)readfua \fR=\fPbool
With readfua option set to 1, read operations include the force
unit access (fua) flag. Default: 0.
generate 8k of data for each command butonly the first 512 bytes will
be used and transferred to the device. The writefua option is ignored
with this selection.
+.RE
+.RE
+.TP
+.BI (nbd)uri \fR=\fPstr
+Specify the NBD URI of the server to test.
+The string is a standard NBD URI (see
+\fIhttps://github.com/NetworkBlockDevice/nbd/tree/master/doc\fR).
+Example URIs:
+.RS
+.RS
+.TP
+\fInbd://localhost:10809\fR
+.TP
+\fInbd+unix:///?socket=/tmp/socket\fR
+.TP
+\fInbds://tlshost/exportname\fR
.SS "I/O depth"
.TP
\fBserialize_overlap\fR tells fio to avoid provoking this behavior by explicitly
serializing in-flight I/Os that have a non-zero overlap. Note that setting
this option can reduce both performance and the \fBiodepth\fR achieved.
-Additionally this option does not work when \fBio_submit_mode\fR is set to
-offload. Default: false.
+.RS
+.P
+This option only applies to I/Os issued for a single job except when it is
+enabled along with \fBio_submit_mode\fR=offload. In offload mode, fio
+will check for overlap among all I/Os submitted by offload jobs with \fBserialize_overlap\fR
+enabled.
+.P
+Default: false.
+.RE
.TP
.BI io_submit_mode \fR=\fPstr
This option controls how fio submits the I/O to the I/O engine. The default
\fBthinktime_blocks\fR and \fBthinktime_spin\fR.
.TP
.BI thinktime_spin \fR=\fPtime
-Only valid if \fBthinktime\fR is set \- pretend to spend CPU time doing
+Only valid if \fBthinktime\fR is set - pretend to spend CPU time doing
something with the data received, before falling back to sleeping for the
rest of the period specified by \fBthinktime\fR. When the unit is
omitted, the value is interpreted in microseconds.
.TP
.BI thinktime_blocks \fR=\fPint
-Only valid if \fBthinktime\fR is set \- control how many blocks to issue,
+Only valid if \fBthinktime\fR is set - control how many blocks to issue,
before waiting \fBthinktime\fR usecs. If not set, defaults to 1 which will make
fio wait \fBthinktime\fR usecs after every block. This effectively makes any
queue depth setting redundant, since no more than 1 I/O will be queued
.TP
.BI rate \fR=\fPint[,int][,int]
Cap the bandwidth used by this job. The number is in bytes/sec, the normal
-suffix rules apply. Comma\-separated values may be specified for reads,
+suffix rules apply. Comma-separated values may be specified for reads,
writes, and trims as described in \fBblocksize\fR.
.RS
.P
.TP
.BI rate_min \fR=\fPint[,int][,int]
Tell fio to do whatever it can to maintain at least this bandwidth. Failing
-to meet this requirement will cause the job to exit. Comma\-separated values
+to meet this requirement will cause the job to exit. Comma-separated values
may be specified for reads, writes, and trims as described in
\fBblocksize\fR.
.TP
Cap the bandwidth to this number of IOPS. Basically the same as
\fBrate\fR, just specified independently of bandwidth. If the job is
given a block size range instead of a fixed value, the smallest block size
-is used as the metric. Comma\-separated values may be specified for reads,
+is used as the metric. Comma-separated values may be specified for reads,
writes, and trims as described in \fBblocksize\fR.
.TP
.BI rate_iops_min \fR=\fPint[,int][,int]
If fio doesn't meet this rate of I/O, it will cause the job to exit.
-Comma\-separated values may be specified for reads, writes, and trims as
+Comma-separated values may be specified for reads, writes, and trims as
described in \fBblocksize\fR.
.TP
.BI rate_process \fR=\fPstr
defaults to 100.0, meaning that all I/Os must be equal or below to the value
set by \fBlatency_target\fR.
.TP
+.BI latency_run \fR=\fPbool
+Used with \fBlatency_target\fR. If false (default), fio will find the highest
+queue depth that meets \fBlatency_target\fR and exit. If true, fio will continue
+running and try to meet \fBlatency_target\fR by adjusting queue depth.
+.TP
.BI max_latency \fR=\fPtime
If set, fio will exit the job with an ETIMEDOUT error if it exceeds this
maximum latency. When the unit is omitted, the value is interpreted in
\fBblktrace\fR\|(8) for how to capture such logging data. For blktrace
replay, the file needs to be turned into a blkparse binary data file first
(`blkparse <device> \-o /dev/null \-d file_for_fio.bin').
+You can specify a number of files by separating the names with a ':' character.
+See the \fBfilename\fR option for information on how to escape ':'
+characters within the file names. These files will be sequentially assigned to
+job clones created by \fBnumjobs\fR.
+.TP
+.BI read_iolog_chunked \fR=\fPbool
+Determines how iolog is read. If false (default) entire \fBread_iolog\fR will
+be read at once. If selected true, input from iolog will be read gradually.
+Useful when iolog is very large, or it is generated.
+.TP
+.BI merge_blktrace_file \fR=\fPstr
+When specified, rather than replaying the logs passed to \fBread_iolog\fR,
+the logs go through a merge phase which aggregates them into a single blktrace.
+The resulting file is then passed on as the \fBread_iolog\fR parameter. The
+intention here is to make the order of events consistent. This limits the
+influence of the scheduler compared to replaying multiple blktraces via
+concurrent jobs.
+.TP
+.BI merge_blktrace_scalars \fR=\fPfloat_list
+This is a percentage based option that is index paired with the list of files
+passed to \fBread_iolog\fR. When merging is performed, scale the time of each
+event by the corresponding amount. For example,
+`\-\-merge_blktrace_scalars="50:100"' runs the first trace in halftime and the
+second trace in realtime. This knob is separately tunable from
+\fBreplay_time_scale\fR which scales the trace during runtime and will not
+change the output of the merge unlike this option.
+.TP
+.BI merge_blktrace_iters \fR=\fPfloat_list
+This is a whole number option that is index paired with the list of files
+passed to \fBread_iolog\fR. When merging is performed, run each trace for
+the specified number of iterations. For example,
+`\-\-merge_blktrace_iters="2:1"' runs the first trace for two iterations
+and the second trace for one iteration.
.TP
.BI replay_no_stall \fR=\fPbool
When replaying I/O with \fBread_iolog\fR the default behavior is to
device accesses.
.TP
.BI replay_align \fR=\fPint
-Force alignment of I/O offsets and lengths in a trace to this power of 2
-value.
+Force alignment of the byte offsets in a trace to this value. The value
+must be a power of 2.
.TP
.BI replay_scale \fR=\fPint
-Scale sector offsets down by this factor when replaying traces.
+Scale bye offsets down by this factor when replaying traces. Should most
+likely use \fBreplay_align\fR as well.
.SS "Threads, processes and job synchronization"
.TP
.BI replay_skip \fR=\fPstr
Set the I/O priority value of this job. Linux limits us to a positive value
between 0 and 7, with 0 being the highest. See man
\fBionice\fR\|(1). Refer to an appropriate manpage for other operating
-systems since meaning of priority may differ.
+systems since meaning of priority may differ. For per-command priority
+setting, see I/O engine specific `cmdprio_percentage` and `hipri_percentage`
+options.
.TP
.BI prioclass \fR=\fPint
-Set the I/O priority class. See man \fBionice\fR\|(1).
+Set the I/O priority class. See man \fBionice\fR\|(1). For per-command
+priority setting, see I/O engine specific `cmdprio_percentage` and `hipri_percent`
+options.
.TP
.BI cpus_allowed \fR=\fPstr
Controls the same options as \fBcpumask\fR, but accepts a textual
.RE
.P
\fBshared\fR is the default behavior, if the option isn't specified. If
-\fBsplit\fR is specified, then fio will will assign one cpu per job. If not
+\fBsplit\fR is specified, then fio will assign one cpu per job. If not
enough CPUs are given for the jobs listed, then fio will roundrobin the CPUs
in the set.
.RE
flow. See \fBflow\fR.
.TP
.BI flow \fR=\fPint
-Weight in token\-based flow control. If this value is used, then there is
+Weight in token-based flow control. If this value is used, then there is
a 'flow counter' which is used to regulate the proportion of activity between
two or more jobs. Fio attempts to keep this flow counter near zero. The
\fBflow\fR parameter stands for how much should be added or subtracted to the
\fBgroup_reporting\fR.
.TP
.BI exitall
-By default, fio will continue running all other jobs when one job finishes
-but sometimes this is not the desired action. Setting \fBexitall\fR will
-instead make fio terminate all other jobs when one job finishes.
+By default, fio will continue running all other jobs when one job finishes.
+Sometimes this is not the desired action. Setting \fBexitall\fR will instead
+make fio terminate all jobs in the same group, as soon as one job of that
+group finishes.
+.TP
+.BI exit_what
+By default, fio will continue running all other jobs when one job finishes.
+Sometimes this is not the desired action. Setting \fBexit_all\fR will instead
+make fio terminate all jobs in the same group. The option \fBexit_what\fR
+allows to control which jobs get terminated when \fBexitall\fR is enabled. The
+default is \fBgroup\fR and does not change the behaviour of \fBexitall\fR. The
+setting \fBall\fR terminates all jobs. The setting \fBstonewall\fR terminates
+all currently running jobs across all groups and continues execution with the
+next stonewalled group.
.TP
.BI exec_prerun \fR=\fPstr
Before running this job, issue the command specified through
given is a read or random read, fio will assume that it should verify a
previously written file. If the data direction includes any form of write,
the verify will be of the newly written data.
+.P
+To avoid false verification errors, do not use the norandommap option when
+verifying data with async I/O engines and I/O depths > 1. Or use the
+norandommap and the lfsr random generator together to avoid writing to the
+same offset with muliple outstanding I/Os.
.RE
.TP
.BI verify_offset \fR=\fPint
data from the rolling collection window. Threshold limits can be expressed
as a fixed value or as a percentage of the mean in the collection window.
.RS
+.P
+When using this feature, most jobs should include the \fBtime_based\fR
+and \fBruntime\fR options or the \fBloops\fR option so that fio does not
+stop running after it has covered the full size of the specified file(s)
+or device(s).
+.RS
.RS
.TP
.B iops
It may sometimes be interesting to display statistics for groups of jobs as
a whole instead of for each individual job. This is especially true if
\fBnumjobs\fR is used; looking at individual thread/process output
-quickly becomes unwieldy. To see the final report per\-group instead of
-per\-job, use \fBgroup_reporting\fR. Jobs in a file will be part of the
+quickly becomes unwieldy. To see the final report per-group instead of
+per-job, use \fBgroup_reporting\fR. Jobs in a file will be part of the
same reporting group, unless if separated by a \fBstonewall\fR, or by
using \fBnew_group\fR.
.TP
.TP
.BI write_iops_log \fR=\fPstr
Same as \fBwrite_bw_log\fR, but writes an IOPS file (e.g.
-`name_iops.x.log') instead. See \fBwrite_bw_log\fR for
-details about the filename format and the \fBLOG FILE FORMATS\fR section for how data
-is structured within the file.
+`name_iops.x.log`) instead. Because fio defaults to individual
+I/O logging, the value entry in the IOPS log will be 1 unless windowed
+logging (see \fBlog_avg_msec\fR) has been enabled. See
+\fBwrite_bw_log\fR for details about the filename format and \fBLOG
+FILE FORMATS\fR for how data is structured within the file.
.TP
.BI log_avg_msec \fR=\fPint
By default, fio will log an entry in the iops, latency, or bw log for every
.TP
.BI log_unix_epoch \fR=\fPbool
If set, fio will log Unix timestamps to the log files produced by enabling
-write_type_log for each log type, instead of the default zero\-based
+write_type_log for each log type, instead of the default zero-based
timestamps.
.TP
.BI block_error_percentiles \fR=\fPbool
-If set, record errors in trim block\-sized units from writes and trims and
+If set, record errors in trim block-sized units from writes and trims and
output a histogram of how many trims it took to get to errors, and what kind
of error was encountered.
.TP
Disable measurements of throughput/bandwidth numbers. See
\fBdisable_lat\fR.
.TP
+.BI slat_percentiles \fR=\fPbool
+Report submission latency percentiles. Submission latency is not recorded
+for synchronous ioengines.
+.TP
.BI clat_percentiles \fR=\fPbool
-Enable the reporting of percentiles of completion latencies. This option is
-mutually exclusive with \fBlat_percentiles\fR.
+Report completion latency percentiles.
.TP
.BI lat_percentiles \fR=\fPbool
-Enable the reporting of percentiles of I/O latencies. This is similar to
-\fBclat_percentiles\fR, except that this includes the submission latency.
-This option is mutually exclusive with \fBclat_percentiles\fR.
+Report total latency percentiles. Total latency is the sum of submission
+latency and completion latency.
.TP
.BI percentile_list \fR=\fPfloat_list
-Overwrite the default list of percentiles for completion latencies and the
-block error histogram. Each number is a floating number in the range
+Overwrite the default list of percentiles for latencies and the
+block error histogram. Each number is a floating point number in the range
(0,100], and the maximum length of the list is 20. Use ':' to separate the
-numbers, and list the numbers in ascending order. For example,
-`\-\-percentile_list=99.5:99.9' will cause fio to report the values of
-completion latency below which 99.5% and 99.9% of the observed latencies
-fell, respectively.
+numbers. For example, `\-\-percentile_list=99.5:99.9' will cause fio to
+report the latency durations below which 99.5% and 99.9% of the observed
+latencies fell, respectively.
.TP
.BI significant_figures \fR=\fPint
If using \fB\-\-output\-format\fR of `normal', set the significant figures
.TP
.BI continue_on_error \fR=\fPstr
Normally fio will exit the job on the first observed failure. If this option
-is set, fio will continue the job when there is a 'non\-fatal error' (EIO or
+is set, fio will continue the job when there is a 'non-fatal error' (EIO or
EILSEQ) until the runtime is exceeded or the I/O size specified is
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
Continue on all errors.
.TP
.B 0
-Backward\-compatible alias for 'none'.
+Backward-compatible alias for 'none'.
.TP
.B 1
-Backward\-compatible alias for 'all'.
+Backward-compatible alias for 'all'.
.RE
.RE
.TP
.BI ignore_error \fR=\fPstr
Sometimes you want to ignore some errors during test in that case you can
specify error list for each error type, instead of only being able to
-ignore the default 'non\-fatal error' using \fBcontinue_on_error\fR.
+ignore the default 'non-fatal error' using \fBcontinue_on_error\fR.
`ignore_error=READ_ERR_LIST,WRITE_ERR_LIST,VERIFY_ERR_LIST' errors for
given error type is separated with ':'. Error may be symbol ('ENOSPC', 'ENOMEM')
or integer. Example:
Thread initialized, waiting or generating necessary data.
.TP
.B p
-Thread running pre\-reading file(s).
+Thread running pre-reading file(s).
.TP
.B /
Thread is in ramp period.
.B bw
Aggregate bandwidth of threads in this group followed by the
minimum and maximum bandwidth of all the threads in this group.
-Values outside of brackets are power\-of\-2 format and those
-within are the equivalent value in a power\-of\-10 format.
+Values outside of brackets are power-of-2 format and those
+within are the equivalent value in a power-of-10 format.
.TP
.B io
Aggregate I/O performed of all threads in this group. The
A description of this job goes here.
.fi
.P
-The job description (if provided) follows on a second line.
+The job description (if provided) follows on a second line for terse v2.
+It appears on the same line for other terse versions.
.P
To enable terse output, use the \fB\-\-minimal\fR or
`\-\-output\-format=terse' command line options. The
.nf
terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth;read_iops;read_runtime_ms;read_slat_min;read_slat_max;read_slat_mean;read_slat_dev;read_clat_min;read_clat_max;read_clat_mean;read_clat_dev;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min;read_lat_max;read_lat_mean;read_lat_dev;read_bw_min;read_bw_max;read_bw_agg_pct;read_bw_mean;read_bw_dev;write_kb;write_bandwidth;write_iops;write_runtime_ms;write_slat_min;write_slat_max;write_slat_mean;write_slat_dev;write_clat_min;write_clat_max;write_clat_mean;write_clat_dev;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min;write_lat_max;write_lat_mean;write_lat_dev;write_bw_min;write_bw_max;write_bw_agg_pct;write_bw_mean;write_bw_dev;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util
.fi
+.P
+In client/server mode terse output differs from what appears when jobs are run
+locally. Disk utilization data is omitted from the standard terse output and
+for v3 and later appears on its own separate line at the end of each terse
+reporting cycle.
.SH JSON OUTPUT
The \fBjson\fR output format is intended to be both human readable and convenient
for automated parsing. For the most part its sections mirror those of the
100,864ns to complete, and 7529 I/Os required 107,008ns to complete.
.P
Also included with fio is a Python script \fBfio_jsonplus_clat2csv\fR that takes
-json+ output and generates CSV\-formatted latency data suitable for plotting.
+json+ output and generates CSV-formatted latency data suitable for plotting.
.P
The latency durations actually represent the midpoints of latency intervals.
For details refer to `stat.h' in the fio source.
Trim the given file from the given `offset' for `length' bytes.
.RE
.RE
+.SH I/O REPLAY \- MERGING TRACES
+Colocation is a common practice used to get the most out of a machine.
+Knowing which workloads play nicely with each other and which ones don't is
+a much harder task. While fio can replay workloads concurrently via multiple
+jobs, it leaves some variability up to the scheduler making results harder to
+reproduce. Merging is a way to make the order of events consistent.
+.P
+Merging is integrated into I/O replay and done when a \fBmerge_blktrace_file\fR
+is specified. The list of files passed to \fBread_iolog\fR go through the merge
+process and output a single file stored to the specified file. The output file is
+passed on as if it were the only file passed to \fBread_iolog\fR. An example would
+look like:
+.RS
+.P
+$ fio \-\-read_iolog="<file1>:<file2>" \-\-merge_blktrace_file="<output_file>"
+.RE
+.P
+Creating only the merged file can be done by passing the command line argument
+\fBmerge-blktrace-only\fR.
+.P
+Scaling traces can be done to see the relative impact of any particular trace
+being slowed down or sped up. \fBmerge_blktrace_scalars\fR takes in a colon
+separated list of percentage scalars. It is index paired with the files passed
+to \fBread_iolog\fR.
+.P
+With scaling, it may be desirable to match the running time of all traces.
+This can be done with \fBmerge_blktrace_iters\fR. It is index paired with
+\fBread_iolog\fR just like \fBmerge_blktrace_scalars\fR.
+.P
+In an example, given two traces, A and B, each 60s long. If we want to see
+the impact of trace A issuing IOs twice as fast and repeat trace A over the
+runtime of trace B, the following can be done:
+.RS
+.P
+$ fio \-\-read_iolog="<trace_a>:"<trace_b>" \-\-merge_blktrace_file"<output_file>" \-\-merge_blktrace_scalars="50:100" \-\-merge_blktrace_iters="2:1"
+.RE
+.P
+This runs trace A at 2x the speed twice for approximately the same runtime as
+a single run of trace B.
.SH CPU IDLENESS PROFILING
In some cases, we want to understand CPU overhead in a test. For example, we
test patches for the specific goodness of whether they reduce CPU usage.
I/O is a TRIM
.RE
.P
-The entry's `block size' is always in bytes. The `offset' is the offset, in bytes,
-from the start of the file, for that particular I/O. The logging of the offset can be
+The entry's `block size' is always in bytes. The `offset' is the position in bytes
+from the start of the file for that particular I/O. The logging of the offset can be
toggled with \fBlog_offset\fR.
.P
-Fio defaults to logging every individual I/O. When IOPS are logged for individual
-I/Os the `value' entry will always be 1. If windowed logging is enabled through
-\fBlog_avg_msec\fR, fio logs the average values over the specified period of time.
-If windowed logging is enabled and \fBlog_max_value\fR is set, then fio logs
-maximum values in that window instead of averages. Since `data direction', `block size'
-and `offset' are per\-I/O values, if windowed logging is enabled they
-aren't applicable and will be 0.
+Fio defaults to logging every individual I/O but when windowed logging is set
+through \fBlog_avg_msec\fR, either the average (by default) or the maximum
+(\fBlog_max_value\fR is set) `value' seen over the specified period of time
+is recorded. Each `data direction' seen within the window period will aggregate
+its values in a separate row. Further, when using windowed logging the `block
+size' and `offset' entries will always contain 0.
.SH CLIENT / SERVER
-Normally fio is invoked as a stand\-alone application on the machine where the
+Normally fio is invoked as a stand-alone application on the machine where the
I/O workload should be generated. However, the backend and frontend of fio can
be run separately i.e., the fio server can generate an I/O workload on the "Device
Under Test" while being controlled by a client on another machine.
$ fio \-\-client=host.list <job file(s)>
.RE
.P
-In this mode, you cannot input server\-specific parameters or job files \-\- all
+In this mode, you cannot input server-specific parameters or job files \-\- all
servers receive the same job file.
.P
In order to let `fio \-\-client' runs use a shared filesystem from multiple
/mnt/nfs/fio/192.168.10.121.fileio.tmp
.PD
.RE
+.P
+Terse output in client/server mode will differ slightly from what is produced
+when fio is run in stand-alone mode. See the terse output section for details.
.SH AUTHORS
.B fio
was written by Jens Axboe <axboe@kernel.dk>.
projects / fio.git / blobdiff