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?
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
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
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.
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).
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.
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.
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.
+ Unfortuantely 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.
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
+ 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
"jobname_type.x.log" is used,where x is the index of the job
specified period of time, reducing the resolution of the log.
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
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
[psyncv2] hipri Set RWF_HIPRI on IO, indicating to the kernel that
it's of higher priority than normal.
-[cpu] cpuload=int Attempt to use the specified percentage of CPU cycles.
+[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.
[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
projects / fio.git / blobdiff