fio
---

fio is a tool that will spawn a number of thread doing a particular
type of io action as specified by the user. fio takes a number of
global parameters, each inherited by the thread unless otherwise
parameters given to them overriding that setting is given.

Options
-------

$ fio
	-s IO is sequential
	-b block size in KiB for each io
	-t <sec> Runtime in seconds
	-w Write statistics
	-r For random io, sequence must be repeatable
	-o <on> Use direct IO is 1, buffered if 0
	-f <file> Read <file> for job descriptions

	<jobs>

The <jobs> format is as follows:

	rw=0/1		0 is read, 1 is write
	prio=x		Run io at prio X, 0-7 is the kernel allowed range
	prioclass=x	Run io at prio class X
	file=foo	Do the io to file foo
	bs=x		Thread blocksize is x KiB
	direct=x	1 for direct IO, 0 for buffered IO
	delay=x		Delay x useconds before each io
	random		IO is randomized
	sequential	IO is sequential
	rate=x		Throttle rate to x KiB/sec
	cpumask=x	Allow job to run on CPUs defined by mask


Examples using cmd line jobs
----------------------------

Spawn 2 threads, one read and one writer. Both threads want direct and
sequential io, set these as global options. The reader wants a 4kb block
size and the writer a 16kb block size, set those as thread options.

$ fio -o1 -s "{rw=0,file=read_file,bs=4096}" "{rw=1,file=write_file,bs=16384}"

Spawn 3 reader threads doing io at priorities 0, 3, and 6. The highest
prio thread wants direct io, the others buffered. All want a 4kb block
size.

$ fio -o0 -s -b4096 "{rw=0,file=rf1,prio=6}" "{rw=0,file=rf2,prio=3}" "{rw=0,file=rf3,prio=0,direct=1}"

Examples using a job file
-------------------------

A sample job file doing the same as above would look like this:

[read_file]
rw=0
bs=4096

[write_file]
rw=1
bs=16384

And fio would be invoked as:

$ fio -o1 -s -f file_with_above

The second example would look like this:

[rf1]
rw=0
prio=6

[rf2]
rw=0
prio=3

[rf3]
rw=0
prio=0
direct=1

And fio would be invoked as:

$ fio -o0 -s -b4096 -f file_with_above