7. Terse output
8. Trace file format
9. CPU idleness profiling
+10. Verification and triggers
+11. Log File Formats
+
1.0 Overview and history
------------------------
IO engine How do we issue io? We could be memory mapping the
file, we could be using regular read/write, we
- could be using splice, async io, syslet, or even
- SG (SCSI generic sg).
+ could be using splice, async io, or even SG
+ (SCSI generic sg).
IO depth If the io engine is async, how large a queuing
depth do we want to maintain?
1k:4k. If the option allows two sets of ranges, they can be
specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see
int.
-float_list A list of floating numbers, separated by a ':' character.
+float_list A list of floating point numbers, separated by a ':' character.
With the above in mind, here follows the complete list of fio job
parameters.
filename=str Fio normally makes up a filename based on the job name,
thread number, and file number. If you want to share
files between threads in a job or several jobs, specify
- a filename for each of them to override the default. If
- the ioengine used is 'net', the filename is the host, port,
- and protocol to use in the format of =host,port,protocol.
- See ioengine=net for more. If the ioengine is file based, you
- can specify a number of files by separating the names with a
- ':' colon. So if you wanted a job to open /dev/sda and /dev/sdb
- as the two working files, you would use
- filename=/dev/sda:/dev/sdb. 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).
+ a filename for each of them to override the default.
+ If the ioengine is file based, you can specify a number of
+ files by separating the names with a ':' colon. So if you
+ wanted a job to open /dev/sda and /dev/sdb as the two working
+ files, you would use filename=/dev/sda:/dev/sdb. 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).
If the wanted filename does need to include a colon, then
escape that with a '\' character. For instance, if the filename
is "/dev/dsk/foo@3,0:c", then you would use
default of $jobname.$jobnum.$filenum will be used if
no other format specifier is given.
+unique_filename=bool To avoid collisions between networked clients, fio
+ defaults to prefixing any generated filenames (with a directory
+ specified) with the source of the client connecting. To disable
+ this behavior, set this option to 0.
+
opendir=str Tell fio to recursively add any file it can find in this
directory and down the file system tree.
trimwrite Mixed trims and writes. Blocks will be
trimmed first, then written to.
+ Fio defaults to read if the option is not specified.
For the mixed io types, the default is to split them 50/50.
For certain types of io the result may still be skewed a bit,
since the speed may be different. It is possible to specify
the next. Multiple files can still be
open depending on 'openfiles'.
- The string can have a number appended, indicating how
- often to switch to a new file. So if option random:4 is
- given, fio will switch to a new random file after 4 ios
- have been issued.
+ zipf Use a zipfian distribution to decide what file
+ to access.
+
+ pareto Use a pareto distribution to decide what file
+ to access.
+
+ gauss Use a gaussian (normal) distribution to decide
+ what file to access.
+
+ For random, roundrobin, and sequential, 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
+ distributions, a floating point postfix can be given to
+ influence how the distribution is skewed. See
+ 'random_distribution' for a description of how that would work.
ioengine=str Defines how the job issues io to the file. The following
types are defined:
sync Basic read(2) or write(2) io. lseek(2) is
used to position the io location.
- psync Basic pread(2) or pwrite(2) io.
+ psync Basic pread(2) or pwrite(2) io. Default on all
+ supported operating systems except for Windows.
vsync Basic readv(2) or writev(2) IO.
- psyncv Basic preadv(2) or pwritev(2) IO.
+ pvsync Basic preadv(2) or pwritev(2) IO.
+
+ pvsync2 Basic preadv2(2) or pwritev2(2) IO.
libaio Linux native asynchronous io. Note that Linux
may only support queued behaviour with
solarisaio Solaris native asynchronous io.
windowsaio Windows native asynchronous io.
+ Default on Windows.
mmap File is memory mapped and data copied
to/from using memcpy(3).
vmsplice(2) to transfer data from user
space to the kernel.
- syslet-rw Use the syslet system calls to make
- regular read/write async.
-
sg SCSI generic sg v3 io. May either be
synchronous using the SG_IO ioctl, or if
the target is an sg character device
cpuio Doesn't transfer any data, but burns CPU
cycles according to the cpuload= and
- cpucycle= options. Setting cpuload=85
+ cpuchunks= options. Setting cpuload=85
will cause that job to do nothing but burn
85% of the CPU. In case of SMP machines,
use numjobs=<no_of_cpu> to get desired CPU
usage, as the cpuload only loads a single
- CPU at the desired rate.
+ CPU at the desired rate. A job never finishes
+ unless there is at least one non-cpuio job.
guasi The GUASI IO engine is the Generic Userspace
Asyncronous Syscall Interface approach
cannot be modified. So random writes are not
possible. To imitate this, libhdfs engine
creates bunch of small files, and engine will
- pick a file out of those files based on the
- offset enerated by fio backend. Each jobs uses
+ pick a file out of those files based on the
+ offset generated by fio backend. Each jobs uses
it's own connection to HDFS.
mtd Read, write and erase an MTD character device
overwriting. The writetrim mode works well
for this constraint.
+ pmemblk Read and write through the NVML libpmemblk
+ interface.
+
+ dev-dax Read and write through a DAX device exposed
+ from persistent memory.
+
external Prefix to specify loading an external
IO engine object file. Append the engine
filename, eg ioengine=external:/tmp/foo.o
iodepth_batch_complete_min=1
iodepth_batch_complete_max=<iodepth>
- which means that we will retrieve at leat 1 IO and up to the
+ which means that we will retrieve at least 1 IO and up to the
whole submitted queue depth. If none of IO has been completed
yet, we will wait.
random Uniform random distribution
zipf Zipf distribution
pareto Pareto distribution
+ gauss Normal (gaussian) distribution
+ zoned Zoned random distribution
When using a zipf or pareto distribution, an input value
is also needed to define the access pattern. For zipf, this
what the given input values will yield in terms of hit rates.
If you wanted to use zipf with a theta of 1.2, you would use
random_distribution=zipf:1.2 as the option. If a non-uniform
- model is used, fio will disable use of the random map.
+ model is used, fio will disable use of the random map. For
+ the gauss distribution, a normal deviation is supplied as
+ a value between 0 and 100.
+
+ For a zoned distribution, fio supports specifying percentages
+ of IO access that should fall within what range of the file or
+ device. For example, given a criteria of:
+
+ 60% of accesses should be to the first 10%
+ 30% of accesses should be to the next 20%
+ 8% of accesses should be to to the next 30%
+ 2% of accesses should be to the next 40%
+
+ we can define that through zoning of the random accesses. For
+ the above example, the user would do:
+
+ random_distribution=zoned:60/10:30/20:8/30:2/40
+
+ similarly to how bssplit works for setting ranges and
+ percentages of block sizes. Like bssplit, it's possible to
+ specify separate zones for reads, writes, and trims. If just
+ one set is given, it'll apply to all of them.
percentage_random=int For a random workload, set how big a percentage should
be random. This defaults to 100%, in which case the workload
and random IO, at the given percentages. It is possible to
set different values for reads, writes, and trim. To do so,
simply use a comma separated list. See blocksize.
-
+
norandommap Normally fio will cover every block of the file when doing
random IO. If this option is given, fio will just get a
new random offset without looking at past io history. This
nice=int Run the job with the given nice value. See man nice(2).
+ On Windows, values less than -15 set the process class to "High";
+ -1 through -15 set "Above Normal"; 1 through 15 "Below Normal";
+ and above 15 "Idle" priority class.
+
prio=int Set the io priority value of this job. Linux limits us to
a positive value between 0 and 7, with 0 being the highest.
- See man ionice(1).
+ See man ionice(1). Refer to an appropriate manpage for
+ other operating systems since meaning of priority may differ.
prioclass=int Set the io priority class. See man ionice(1).
one cpu per job. If not enough CPUs are given for the jobs
listed, then fio will roundrobin the CPUs in the set.
-numa_cpu_nodes=str Set this job running on spcified NUMA nodes' CPUs. The
+numa_cpu_nodes=str Set this job running on specified NUMA nodes' CPUs. The
arguments allow comma delimited list of cpu numbers,
A-B ranges, or 'all'. Note, to enable numa options support,
fio must be built on a system with libnuma-dev(el) installed.
numa_mem_policy=str Set this job's memory policy and corresponding NUMA
- nodes. Format of the argements:
+ nodes. Format of the arguments:
<mode>[:<nodelist>]
`mode' is one of the following memory policy:
default, prefer, bind, interleave, local
thus it will increase the total runtime if a special timeout
or runtime is specified.
+steadystate=str:float
+ss=str:float Define the criterion and limit for assessing steady state
+ performance. The first parameter designates the criterion
+ whereas the second parameter sets the threshold. When the
+ criterion falls below the threshold for the specified duration,
+ the job will stop. For example, iops_slope:0.1% will direct fio
+ to terminate the job when the least squares regression slope
+ falls below 0.1% of the mean IOPS. If group_reporting is
+ enabled this will apply to all jobs in the group. Below is the
+ list of available steady state assessment criteria. All
+ assessments are carried out using only 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.
+ iops Collect IOPS data. Stop the job if all
+ individual IOPS measurements are within the
+ specified limit of the mean IOPS (e.g., iops:2
+ means that all individual IOPS values must be
+ within 2 of the mean, whereas iops:0.2% means
+ that all individual IOPS values must be within
+ 0.2% of the mean IOPS to terminate the job).
+ iops_slope
+ Collect IOPS data and calculate the least
+ squares regression slope. Stop the job if the
+ slope falls below the specified limit.
+ bw Collect bandwidth data. Stop the job if all
+ individual bandwidth measurements are within
+ the specified limit of the mean bandwidth.
+ bw_slope
+ Collect bandwidth data and calculate the least
+ squares regression slope. Stop the job if the
+ slope falls below the specified limit.
+
+steadystate_duration=time
+ss_dur=time A rolling window of this duration will be used to judge whether
+ steady state has been reached. Data will be collected once per
+ second. The default is 0 which disables steady state detection.
+
+steadystate_ramp_time=time
+ss_ramp=time Allow the job to run for the specified duration before
+ beginning data collection for checking the steady state job
+ termination criterion. The default is 0.
+
invalidate=bool Invalidate the buffer/page cache parts for this file prior
to starting io. Defaults to true.
The allowed values are:
malloc Use memory from malloc(3) as the buffers.
+ Default memory type.
shm Use shared memory as the buffers. Allocated
through shmget(2).
location should point there. So if it's mounted in /huge,
you would use mem=mmaphuge:/huge/somefile.
-iomem_align=int This indiciates the memory alignment of the IO memory buffers.
+iomem_align=int This indicates the memory alignment of the IO memory buffers.
Note that the given alignment is applied to the first IO unit
buffer, if using iodepth the alignment of the following buffers
are given by the bs used. In other words, if using a bs that is
default is to wait for each job to finish.
bwavgtime=int Average the calculated bandwidth over the given time. Value
- is specified in milliseconds.
+ is specified in milliseconds. If the job also does bandwidth
+ logging through 'write_bw_log', then the minimum of this option
+ and 'log_avg_msec' will be used. Default: 500ms.
iopsavgtime=int Average the calculated IOPS over the given time. Value
- is specified in milliseconds.
+ is specified in milliseconds. If the job also does IOPS logging
+ through 'write_iops_log', then the minimum of this option and
+ 'log_avg_msec' will be used. Default: 500ms.
-create_serialize=bool If true, serialize the file creating for the jobs.
+create_serialize=bool If true, serialize the file creation for the jobs.
This may be handy to avoid interleaving of data
files, which may greatly depend on the filesystem
used and even the number of processors in the system.
starting the given IO operation. This will also clear
the 'invalidate' flag, since it is pointless to pre-read
and then drop the cache. This will only work for IO engines
- that are seekable, since they allow you to read the same data
+ that are seek-able, since they allow you to read the same data
multiple times. Thus it will not work on eg network or splice
IO.
runs of that job would then waste time recreating the file
set again and again.
+unlink_each_loop=bool Unlink job files after each iteration or loop.
+
loops=int Run the specified number of iterations of this job. Used
to repeat the same workload a given number of times. Defaults
to 1.
crc32c Use a crc32c sum of the data area and store
it in the header of each block.
- crc32c-intel Use hardware assisted crc32c calcuation
+ crc32c-intel Use hardware assisted crc32c calculation
provided on SSE4.2 enabled processors. Falls
back to regular software crc32c, if not
supported by the system.
be a hex number that starts with either "0x" or "0X". Use
with verify=str. Also, verify_pattern supports %o format,
which means that for each block offset will be written and
- then verifyied back, e.g.:
+ then verified back, e.g.:
verify_pattern=%o
replay_no_stall=int When replaying I/O with read_iolog the default behavior
is to attempt to respect the time stamps within the log and
- replay them with the appropriate delay between IOPS. By
+ replay them with the appropriate delay between IOPS. By
setting this variable fio will not respect the timestamps and
attempt to replay them as fast as possible while still
- respecting ordering. The result is the same I/O pattern to a
+ respecting ordering. The result is the same I/O pattern to a
given device, but different timings.
replay_redirect=str While replaying I/O patterns using read_iolog the
mapping. Replay_redirect causes all IOPS to be replayed onto
the single specified device regardless of the device it was
recorded from. i.e. replay_redirect=/dev/sdc would cause all
- IO in the blktrace to be replayed onto /dev/sdc. This means
- multiple devices will be replayed onto a single, if the trace
- contains multiple devices. If you want multiple devices to be
- replayed concurrently to multiple redirected devices you must
- blkparse your trace into separate traces and replay them with
- independent fio invocations. Unfortuantely this also breaks
- the strict time ordering between multiple device accesses.
+ IO in the blktrace or iolog to be replayed onto /dev/sdc.
+ This means multiple devices will be replayed onto a single
+ device, if the trace contains multiple devices. If you want
+ multiple devices to be replayed concurrently to multiple
+ redirected devices you must blkparse your trace into separate
+ traces and replay them with independent fio invocations.
+ Unfortunately this also breaks the strict time ordering
+ between multiple device accesses.
replay_align=int Force alignment of IO offsets and lengths in a trace
to this power of 2 value.
filename. For this option, the suffix is _bw.x.log, where
x is the index of the job (1..N, where N is the number of
jobs). If 'per_job_logs' is false, then the filename will not
- include the job index.
+ include the job index. See 'Log File Formats'.
write_lat_log=str Same as write_bw_log, except that this option stores io
submission, completion, and total latencies instead. If no
The actual log names will be foo_slat.x.log, foo_clat.x.log,
and foo_lat.x.log, where x is the index of the job (1..N,
where N is the number of jobs). This helps fio_generate_plot
- fine the logs automatically. If 'per_job_logs' is false, then
- the filename will not include the job index.
-
+ find the logs automatically. If 'per_job_logs' is false, then
+ the filename will not include the job index. See 'Log File
+ Formats'.
+
+write_hist_log=str Same as write_lat_log, but writes I/O completion
+ latency histograms. If no filename is given with this option, the
+ default filename of "jobname_clat_hist.x.log" is used, where x is
+ the index of the job (1..N, where N is the number of jobs). Even
+ if the filename is given, fio will still append the type of log.
+ If per_job_logs is false, then the filename will not include the
+ job index. See 'Log File Formats'.
write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is
given with this option, the default filename of
(1..N, where N is the number of jobs). Even if the filename
is given, fio will still append the type of log. If
'per_job_logs' is false, then the filename will not include
- the job index.
+ the job index. See 'Log File Formats'.
log_avg_msec=int By default, fio will log an entry in the iops, latency,
or bw log for every IO that completes. When writing to the
disk log, that can quickly grow to a very large size. Setting
this option makes fio average the each log entry over the
specified period of time, reducing the resolution of the log.
- Defaults to 0.
+ See log_max_value as well. Defaults to 0, logging all entries.
+
+log_hist_msec=int Same as log_avg_msec, but logs entries for completion
+ latency histograms. Computing latency percentiles from averages of
+ intervals using log_avg_msec is innacurate. Setting this option makes
+ fio log histogram entries over the specified period of time, reducing
+ log sizes for high IOPS devices while retaining percentile accuracy.
+ See log_hist_coarseness as well. Defaults to 0, meaning histogram
+ logging is disabled.
+
+log_hist_coarseness=int Integer ranging from 0 to 6, defining the coarseness
+ of the resolution of the histogram logs enabled with log_hist_msec. For
+ each increment in coarseness, fio outputs half as many bins. Defaults to
+ 0, for which histogram logs contain 1216 latency bins. See
+ 'Log File Formats'.
+
+log_max_value=bool If log_avg_msec is set, fio logs the average over that
+ window. If you instead want to log the maximum value, set this
+ option to 1. Defaults to 0, meaning that averaged values are
+ logged.
log_offset=int If this is set, the iolog options will include the byte
offset for the IO entry as well as the other data values.
the --inflate-log command line parameter. The files will be
stored with a .fz suffix.
+log_unix_epoch=bool 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 timestamps.
+
block_error_percentiles=bool 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
enabled when polling for a minimum of 0 events (eg when
iodepth_batch_complete=0).
-[cpu] cpuload=int Attempt to use the specified percentage of CPU cycles.
+[psyncv2] hipri Set RWF_HIPRI on IO, indicating to the kernel that
+ it's of higher priority than normal.
+
+[cpuio] cpuload=int Attempt to use the specified percentage of CPU cycles.
-[cpu] cpuchunks=int Split the load into cycles of the given time. In
+[cpuio] cpuchunks=int Split the load into cycles of the given time. In
microseconds.
-[cpu] exit_on_io_done=bool Detect when IO threads are done, then exit.
+[cpuio] exit_on_io_done=bool Detect when IO threads are done, then exit.
[netsplice] hostname=str
[net] hostname=str The host name or IP address to use for TCP or UDP based IO.
connections rather than initiating an outgoing connection. The
hostname must be omitted if this option is used.
-[net] pingpong Normaly a network writer will just continue writing data, and
+[net] pingpong Normally a network writer will just continue writing data, and
a network reader will just consume packages. If pingpong=1
is set, a writer will send its normal payload to the reader,
then wait for the reader to send the same payload back. This
[e4defrag] inplace=int
Configure donor file blocks allocation strategy
0(default): Preallocate donor's file on init
- 1 : allocate space immidietly inside defragment event,
+ 1 : allocate space immediately inside defragment event,
and free right after event
+[rbd] clustername=str Specifies the name of the Ceph cluster.
+[rbd] rbdname=str Specifies the name of the RBD.
+[rbd] pool=str Specifies the name of the Ceph pool containing RBD.
+[rbd] clientname=str Specifies the username (without the 'client.' prefix)
+ used to access the Ceph cluster. If the clustername is
+ specified, the clientname shall be the full type.id
+ string. If no type. prefix is given, fio will add
+ 'client.' by default.
+
[mtd] skip_bad=bool Skip operations against known bad blocks.
[libhdfs] hdfsdirectory libhdfs will create chunk in this HDFS directory
-[libhdfs] chunck_size the size of the chunck to use for each file.
+[libhdfs] chunk_size the size of the chunk to use for each file.
6.0 Interpreting the output
cpu= CPU usage. User and system time, along with the number
of context switches this thread went through, usage of
system and user time, and finally the number of major
- and minor page faults.
+ and minor page faults. The CPU utilization numbers are
+ averages for the jobs in that reporting group, while the
+ context and fault counters are summed.
IO depths= The distribution of io depths over the job life time. The
numbers are divided into powers of 2, so for example the
16= entries includes depths up to that value but higher
For this case, fio would wait for the server to send us the write state,
then execute 'ipmi-reboot server' when that happened.
-10.1 Loading verify state
+10.2 Loading verify state
-------------------------
To load store write state, read verification job file must contain
the verify_state_load option. If that is set, fio will load the previously
stored state. For a local fio run this is done by loading the files directly,
and on a client/server run, the server backend will ask the client to send
the files over and load them from there.
+
+
+11.0 Log File Formats
+---------------------
+
+Fio supports a variety of log file formats, for logging latencies, bandwidth,
+and IOPS. The logs share a common format, which looks like this:
+
+time (msec), value, data direction, offset
+
+Time for the log entry is always in milliseconds. The value logged depends
+on the type of log, it will be one of the following:
+
+ Latency log Value is latency in usecs
+ Bandwidth log Value is in KB/sec
+ IOPS log Value is IOPS
+
+Data direction is one of the following:
+
+ 0 IO is a READ
+ 1 IO is a WRITE
+ 2 IO is a TRIM
+
+The offset is the offset, in bytes, from the start of the file, for that
+particular IO. The logging of the offset can be toggled with 'log_offset'.
+
+If windowed logging is enabled through 'log_avg_msec', then fio doesn't log
+individual IOs. Instead of logs the average values over the specified
+period of time. Since 'data direction' and 'offset' are per-IO values,
+they aren't applicable if windowed logging is enabled. If windowed logging
+is enabled and 'log_max_value' is set, then fio logs maximum values in
+that window instead of averages.
projects / fio.git / blobdiff