Linux Certif

Toute la documentation sur la certification Linux LPI

fio

NAME

fio - flexible I/O tester

SYNOPSIS

fio [options] [jobfile]...

DESCRIPTION

fio is a tool that will spawn a number of threads or processes doing a particular type of I/O action as specified by the user. The typical use of fio is to write a job file matching the I/O load one wants to simulate.

OPTIONS

--output=filename

Write output to filename.

--timeout=timeout

Limit run time to timeout seconds.

--latency-log

Generate per-job latency logs.

--bandwidth-log

Generate per-job bandwidth logs.

--minimal

Print statistics in a terse, semicolon-delimited format.

--showcmd=jobfile

Convert jobfile to a set of command-line options.

--readonly

Enable read-only safety checks.

--eta=when

Specifies when real-time ETA estimate should be printed. when may be one of `always', `never' or `auto'.

--section=sec

Only run section sec from job file.

--cmdhelp=command

Print help information for command. May be `all' for all commands.

--debug=type

Enable verbose tracing of various fio actions. May be `all' for all types or individual types seperated by a comma (eg --debug=io,file). `help' will list all available tracing options.

--help

Display usage information and exit.

--version

Display version information and exit.

JOB FILE FORMAT

Job files are in `ini' format. They consist of one or more job definitions, which begin with a job name in square brackets and extend to the next job name. The job name can be any ASCII string except `global', which has a special meaning. Following the job name is a sequence of zero or more parameters, one per line, that define the behavior of the job. Any line starting with a `;' or `#' character is considered a comment and ignored.

If jobfile is specified as `-', the job file will be read from standard input.

Global Section

The global section contains default parameters for jobs specified in the job file. A job is only affected by global sections residing above it, and there may be any number of global sections. Specific job definitions may override any parameter set in global sections.

JOB PARAMETERS

Types

Some parameters may take arguments of a specific type. The types used are:

str

String: a sequence of alphanumeric characters.

int

Integer: a whole number, possibly negative. If prefixed with `0x', the value is assumed to be base 16 (hexadecimal).

siint

SI integer: a whole number, possibly containing a suffix denoting the base unit of the value. Accepted suffixes are `k', 'M' and 'G', denoting kilo (1024), mega (1024*1024) and giga (1024*1024*1024) respectively.

bool

Boolean: a true or false value. `0' denotes false, `1' denotes true.

irange

Integer range: a range of integers specified in the format lower:upper or lower-upper. lower and upper may contain a suffix as described above. If an option allows two sets of ranges, they are separated with a `,' or `/' character. For example: `8-8k/8M-4G'.

Parameter List

name=str

May be used to override the job name. On the command line, this parameter has the special purpose of signalling the start of a new job.

description=str

Human-readable description of the job. It is printed when the job is run, but otherwise has no special purpose.

directory=str

Prefix filenames with this directory. Used to place files in a location other than `./'.

filename=str

fio normally makes up a file name 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 I/O engine used is `net', filename is the host and port to connect to in the format host/port. If the I/O engine is file-based, you can specify a number of files by separating the names with a `:' character. `-' is a reserved name, meaning stdin or stdout, depending on the read/write direction set.

opendir=str

Recursively open any files below directory str.

readwrite=str, rw=str

Type of I/O pattern. Accepted values are:

read

Sequential reads.

write

Sequential writes.

randread

Random reads.

randwrite

Random writes.

rw

Mixed sequential reads and writes.

randrw

Mixed random reads and writes.

For mixed I/O, the default split is 50/50. For random I/O, the number of I/Os to perform before getting a new offset can be specified by appending `:int' to the pattern type. The default is 1.

randrepeat=bool

Seed the random number generator in a predictable way so results are repeatable across runs. Default: true.

fadvise_hint=bool

Disable use of posix_fadvise(2) to advise the kernel what I/O patterns are likely to be issued. Default: true.

size=siint

Total size of I/O for this job. fio will run until this many bytes have been transfered, unless limited by other options (runtime, for instance). Unless nr_files and filesize options are given, this amount will be divided between the available files for the job.

filesize=irange

Individual file sizes. May be a range, in which case fio will select sizes for files at random within the given range, limited to size in total (if that is given). If filesize is not specified, each created file is the same size.

blocksize=siint[,siint], bs=siint[,siint]

Block size for I/O units. Default: 4k. Values for reads and writes can be specified seperately in the format read,write, either of which may be empty to leave that value at its default.

blocksize_range=irange[,irange], bsrange=irange[,irange]

Specify a range of I/O block sizes. The issued I/O unit will always be a multiple of the minimum size, unless blocksize_unaligned is set. Applies to both reads and writes if only one range is given, but can be specified seperately with a comma seperating the values. Example: bsrange=1k-4k,2k-8k. Also (see blocksize).

bssplit=str

This option allows even finer grained control of the block sizes issued, not just even splits between them. With this option, you can weight various block sizes for exact control of the issued IO for a job that has mixed block sizes. The format of the option is bssplit=blocksize/percentage, optionally adding as many definitions as needed seperated by a colon. Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k blocks and 40% 32k blocks.

blocksize_unaligned, bs_unaligned

If set, any size in blocksize_range may be used. This typically won't work with direct I/O, as that normally requires sector alignment.

zero_buffers

Initialise buffers with all zeros. Default: fill buffers with random data.

nrfiles=int

Number of files to use for this job. Default: 1.

openfiles=int

Number of files to keep open at the same time. Default: nrfiles.

file_service_type=str

Defines how files to service are selected. The following types are defined:

random

Choose a file at random

roundrobin

Round robin over open files (default).

The number of I/Os to issue before switching a new file can be specified by appending `:int' to the service type.

ioengine=str

Defines how the job issues I/O. The following types are defined:

sync

Basic read(2) or write(2) I/O. fseek(2) is used to position the I/O location.

psync

Basic pread(2) or pwrite(2) I/O.

vsync

Basic readv(2) or writev(2) I/O. Will emulate queuing by coalescing adjacents IOs into a single submission.

libaio

Linux native asynchronous I/O.

posixaio

glibc POSIX asynchronous I/O using aio_read(3) and aio_write(3).

mmap

File is memory mapped with mmap(2) and data copied using memcpy(3).

splice

splice(2) is used to transfer the data and vmsplice(2) to transfer data from user-space to the kernel.

syslet-rw

Use the syslet system calls to make regular read/write asynchronous.

sg

SCSI generic sg v3 I/O. May be either synchronous using the SG_IO ioctl, or if the target is an sg character device, we use read(2) and write(2) for asynchronous I/O.

null

Doesn't transfer any data, just pretends to. Mainly used to exercise fio itself and for debugging and testing purposes.

net

Transfer over the network. filename must be set appropriately to `host/port' regardless of data direction. If receiving, only the port argument is used.

netsplice

Like net, but uses splice(2) and vmsplice(2) to map data and send/receive.

cpuio

Doesn't transfer any data, but burns CPU cycles according to cpuload and cpucycles parameters.

guasi

The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface approach to asycnronous I/O.
See <http://www.xmailserver.org/guasi-lib.html>.

external

Loads an external I/O engine object file. Append the engine filename as `:enginepath'.

iodepth=int

Number of I/O units to keep in flight against the file. Default: 1.

iodepth_batch=int

Number of I/Os to submit at once. Default: iodepth.

iodepth_low=int

Low watermark indicating when to start filling the queue again. Default: iodepth.

direct=bool

If true, use non-buffered I/O (usually O_DIRECT). Default: false.

buffered=bool

If true, use buffered I/O. This is the opposite of the direct parameter. Default: true.

offset=siint

Offset in the file to start I/O. Data before the offset will not be touched.

fsync=int

How many I/Os to perform before issuing an fsync(2) of dirty data. If 0, don't sync. Default: 0.

overwrite=bool

If writing, setup the file first and do overwrites. Default: false.

end_fsync=bool

Sync file contents when job exits. Default: false.

fsync_on_close=bool

If true, sync file contents on close. This differs from end_fsync in that it will happen on every close, not just at the end of the job. Default: false.

rwmixcycle=int

How many milliseconds before switching between reads and writes for a mixed workload. Default: 500ms.

rwmixread=int

Percentage of a mixed workload that should be reads. Default: 50.

rwmixwrite=int

Percentage of a mixed workload that should be writes. If rwmixread and wrmixwrite are given and do not sum to 100%, the latter of the two overrides the first. Default: 50.

norandommap

Normally fio will cover every block of the file when doing random I/O. If this parameter is given, a new offset will be chosen without looking at past I/O history. This parameter is mutually exclusive with verify.

nice=int

Run job with given nice value. See nice(2).

prio=int

Set I/O priority value of this job between 0 (highest) and 7 (lowest). See ionice(1).

prioclass=int

Set I/O priority class. See ionice(1).

thinktime=int

Stall job for given number of microseconds between issuing I/Os.

thinktime_spin=int

Pretend to spend CPU time for given number of microseconds, sleeping the rest of the time specified by thinktime. Only valid if thinktime is set.

thinktime_blocks=int

Number of blocks to issue before waiting thinktime microseconds. Default: 1.

rate=int

Cap bandwidth used by this job to this number of KiB/s.

ratemin=int

Tell fio to do whatever it can to maintain at least the given bandwidth. Failing to meet this requirement will cause the job to exit.

rate_iops=int

Cap the bandwidth to this number of IOPS. If blocksize is a range, the smallest block size is used as the metric.

rate_iops_min=int

If this rate of I/O is not met, the job will exit.

ratecycle=int

Average bandwidth for rate and ratemin over this number of milliseconds. Default: 1000ms.

cpumask=int

Set CPU affinity for this job. int is a bitmask of allowed CPUs the job may run on. See sched_setaffinity(2).

cpus_allowed=str

Same as cpumask, but allows a comma-delimited list of CPU numbers.

startdelay=int

Delay start of job for the specified number of seconds.

runtime=int

Terminate processing after the specified number of seconds.

time_based

If given, run for the specified runtime duration even if the files are completely read or written. The same workload will be repeated as many times as runtime allows.

invalidate=bool

Invalidate buffer-cache for the file prior to starting I/O. Default: true.

sync=bool

Use synchronous I/O for buffered writes. For the majority of I/O engines, this means using O_SYNC. Default: false.

iomem=str, mem=str

Allocation method for I/O unit buffer. Allowed values are:

malloc

Allocate memory with malloc(3).

shm

Use shared memory buffers allocated through shmget(2).

shmhuge

Same as shm, but use huge pages as backing.

mmap

Use mmap(2) for allocation. Uses anonymous memory unless a filename is given after the option in the format `:file'.

mmaphuge

Same as mmap, but use huge files as backing.

The amount of memory allocated is the maximum allowed blocksize for the job multiplied by iodepth. For shmhuge or mmaphuge to work, the system must have free huge pages allocated. mmaphuge also needs to have hugetlbfs mounted, and file must point there.

hugepage-size=siint

Defines the size of a huge page. Must be at least equal to the system setting. Should be a multiple of 1MiB. Default: 4MiB.

exitall

Terminate all jobs when one finishes. Default: wait for each job to finish.

bwavgtime=int

Average bandwidth calculations over the given time in milliseconds. Default: 500ms.

create_serialize=bool

If true, serialize file creation for the jobs. Default: true.

create_fsync=bool

fsync(2) data file after creation. Default: true.

unlink=bool

Unlink job files when done. Default: false.

loops=int

Specifies the number of iterations (runs of the same workload) of this job. Default: 1.

do_verify=bool

Run the verify phase after a write phase. Only valid if verify is set. Default: true.

verify=str

Method of verifying file contents after each iteration of the job. Allowed values are:

md5 crc16 crc32 crc64 crc7 sha256 sha512

Store appropriate checksum in the header of each block.

meta

Write extra information about each I/O (timestamp, block number, etc.). The block number is verified.

pattern

Fill I/O buffers with a specific pattern that is used to verify. The pattern is specified by appending `:int' to the parameter. int cannot be larger than 32-bits.

null

Pretend to verify. Used for testing internals.

verify_sort=bool

If true, written verify blocks are sorted if fio deems it to be faster to read them back in a sorted manner. Default: true.

verify_offset=siint

Swap the verification header with data somewhere else in the block before writing. It is swapped back before verifying.

verify_interval=siint

Write the verification header for this number of bytes, which should divide blocksize. Default: blocksize.

verify_fatal=bool

If true, exit the job on the first observed verification failure. Default: false.

stonewall

Wait for preceeding jobs in the job file to exit before starting this one. stonewall implies new_group.

new_group

Start a new reporting group. If not given, all jobs in a file will be part of the same reporting group, unless separated by a stonewall.

numjobs=int

Number of clones (processes/threads performing the same workload) of this job. Default: 1.

group_reporting

If set, display per-group reports instead of per-job when numjobs is specified.

thread

Use threads created with pthread_create(3) instead of processes created with fork(2).

zonesize=siint

Divide file into zones of the specified size in bytes. See zoneskip.

zoneskip=siint

Skip the specified number of bytes when zonesize bytes of data have been read.

write_iolog=str

Write the issued I/O patterns to the specified file.

read_iolog=str

Replay the I/O patterns contained in the specified file generated by write_iolog, or may be a blktrace binary file.

write_bw_log

If given, write bandwidth logs of the jobs in this file.

write_lat_log

Same as write_bw_log, but writes I/O completion latencies.

lockmem=siint

Pin the specified amount of memory with mlock(2). Can be used to simulate a smaller amount of memory.

exec_prerun=str

Before running the job, execute the specified command with system(3).

exec_postrun=str

Same as exec_prerun, but the command is executed after the job completes.

ioscheduler=str

Attempt to switch the device hosting the file to the specified I/O scheduler.

cpuload=int

If the job is a CPU cycle-eater, attempt to use the specified percentage of CPU cycles.

cpuchunks=int

If the job is a CPU cycle-eater, split the load into cycles of the given time in milliseconds.

disk_util=bool

Generate disk utilization statistics if the platform supports it. Default: true.

OUTPUT

While running, fio will display the status of the created jobs. For example:

Threads: 1: [_r] [24.8% done] [ 13509/ 8334 kb/s] [eta 00h:01m:31s]

The characters in the first set of brackets denote the current status of each threads. The possible values are:

P

Setup but not started.

C

Thread created.

I

Initialized, waiting.

R

Running, doing sequential reads.

r

Running, doing random reads.

W

Running, doing sequential writes.

w

Running, doing random writes.

M

Running, doing mixed sequential reads/writes.

m

Running, doing mixed random reads/writes.

F

Running, currently waiting for fsync(2).

V

Running, verifying written data.

E

Exited, not reaped by main thread.

-

Exited, thread reaped.

The second set of brackets shows the estimated completion percentage of the current group. The third set shows the read and write I/O rate, respectively. Finally, the estimated run time of the job is displayed.

When fio completes (or is interrupted by Ctrl-C), it will show data for each thread, each group of threads, and each disk, in that order.

Per-thread statistics first show the threads client number, group-id, and error code. The remaining figures are as follows:

io

Number of megabytes of I/O performed.

bw

Average data rate (bandwidth).

runt

Threads run time.

slat

Submission latency minimum, maximum, average and standard deviation. This is the time it took to submit the I/O.

clat

Completion latency minimum, maximum, average and standard deviation. This is the time between submission and completion.

bw

Bandwidth minimum, maximum, percentage of aggregate bandwidth received, average and standard deviation.

cpu

CPU usage statistics. Includes user and system time, number of context switches this thread went through and number of major and minor page faults.

IO depths

Distribution of I/O depths. Each depth includes everything less than (or equal) to it, but greater than the previous depth.

IO issued

Number of read/write requests issued, and number of short read/write requests.

IO latencies

Distribution of I/O completion latencies. The numbers follow the same pattern as IO depths.

The group statistics show:

io

Number of megabytes I/O performed.

aggrb

Aggregate bandwidth of threads in the group.

minb

Minimum average bandwidth a thread saw.

maxb

Maximum average bandwidth a thread saw.

mint

Shortest runtime of threads in the group.

maxt

Longest runtime of threads in the group.

Finally, disk statistics are printed with reads first:

ios

Number of I/Os performed by all groups.

merge

Number of merges in the I/O scheduler.

ticks

Number of ticks we kept the disk busy.

io_queue

Total time spent in the disk queue.

util

Disk utilization.

TERSE OUTPUT

If the --minimal option is given, the results will be printed in a semicolon-delimited format suitable for scripted use. The fields are:

jobname, groupid, error
Read status:

KiB I/O, bandwidth (KiB/s), runtime (ms)
Submission latency:

min, max, mean, standard deviation

Completion latency:

min, max, mean, standard deviation

Bandwidth:

min, max, aggregate percentage of total, mean, standard deviation

Write status:

KiB I/O, bandwidth (KiB/s), runtime (ms)
Submission latency:

min, max, mean, standard deviation

Completion latency:

min, max, mean, standard deviation

Bandwidth:

min, max, aggregate percentage of total, mean, standard deviation

CPU usage:

user, system, context switches, major page faults, minor page faults

IO depth distribution:

<=1, 2, 4, 8, 16, 32, >=64

IO latency distribution (ms):

<=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000, >=2000

text description

AUTHORS

fio was written by Jens Axboe <jens.axboe@oracle.com>.
This man page was written by Aaron Carroll <aaronc@cse.unsw.edu.au> based on documentation by Jens Axboe.

REPORTING BUGS

Report bugs to the fio mailing list <fio-devel@kernel.dk>. See README.

SEE ALSO

For further documentation see HOWTO and README.
Sample jobfiles are available in the examples directory.