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
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
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).
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).
[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.
projects / fio.git / blobdiff