Make nr_thread/nr_process private to backend

[fio.git] / README

fio
---

fio is a tool that will spawn a number of threads or processes 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.
The typical use of fio is to write a job file matching the io load
one wants to simulate.


Source
------

fio resides in a git repo, the canonical place is:

git://git.kernel.dk/fio.git

If you are inside a corporate firewall, git:// may not always work for
you. In that case you can use the http protocol, path is the same:

http://git.kernel.dk/fio.git

Snapshots are frequently generated and they include the git meta data as
well. You can download them here:

http://brick.kernel.dk/snaps/


Binary packages
---------------

Debian:
Starting with Debian "Squeeze", fio packages are part of the official
Debian repository. http://packages.debian.org/search?keywords=fio

Ubuntu:
Starting with Ubuntu 10.04 LTS (aka "Lucid Lynx"), fio packages are part
of the Ubuntu "universe" repository.
http://packages.ubuntu.com/search?keywords=fio

Red Hat, CentOS & Co:
Dag Wieërs has RPMs for Red Hat related distros, find them here:
http://dag.wieers.com/rpm/packages/fio/

Mandriva:
Mandriva has integrated fio into their package repository, so installing
on that distro should be as easy as typing 'urpmi fio'.

Solaris:
Packages for Solaris are available from OpenCSW. Install their pkgutil
tool (http://www.opencsw.org/get-it/pkgutil/) and then install fio via
'pkgutil -i fio'.

Windows:
Bruce Cran <bruce@cran.org.uk> has fio packages for Windows at
http://www.bluestop.org/fio/ .


Mailing list
------------

There's a mailing list associated with fio. It's meant for general
discussion, bug reporting, questions, and development - basically anything
that has to do with fio. An automated mail detailing recent commits is
automatically sent to the list at most daily. The list address is
fio@vger.kernel.org, subscribe by sending an email to
majordomo@vger.kernel.org with

subscribe fio

in the body of the email. Archives can be found here:

http://www.spinics.net/lists/fio/

and archives for the old list can be found here:

http://maillist.kernel.dk/fio-devel/


Building
--------

Just type 'make' and 'make install'.

Note that GNU make is required. On BSD it's available from devel/gmake;
on Solaris it's in the SUNWgmake package. On platforms where GNU make
isn't the default, type 'gmake' instead of 'make'.

If your compile fails with an error like this:

    CC gettime.o
In file included from fio.h:23,
                 from gettime.c:8:
os/os.h:15:20: error: libaio.h: No such file or directory
In file included from gettime.c:8:
fio.h:119: error: field 'iocb' has incomplete type
make: *** [gettime.o] Error 1

Check that you have the libaio development package installed. On RPM
based distros, it's typically called libaio-devel.


Windows
-------

On Windows Cygwin (http://www.cygwin.com/) is required in order to
build fio. To create an MSI installer package install WiX 3.7 from
http://wixtoolset.org and run dobuild.cmd from the
os/windows directory.

How to compile FIO on 64-bit Windows:

 1. Install Cygwin (http://www.cygwin.com/setup.exe). Install 'make' and all
    packages starting with 'mingw64-i686' and 'mingw64-x86_64'.
 2. Download ftp://sourceware.org/pub/pthreads-win32/prebuilt-dll-2-9-1-release/dll/x64/pthreadGC2.dll
    and copy to the fio source directory.
 3. Open the Cygwin Terminal.
 4. Go to the fio directory (source files).
 5. Run 'make clean'.
 6. Run 'make'.

To build fio on 32-bit Windows, download x86/pthreadGC2.dll instead and do
'./configure --build-32bit-win=yes' before 'make'.

It's recommended that once built or installed, fio be run in a Command Prompt
or other 'native' console such as console2, since there are known to be display
and signal issues when running it under a Cygwin shell
(see http://code.google.com/p/mintty/issues/detail?id=56 for details).


Command line
------------

$ fio
	--debug			Enable some debugging options (see below)
	--parse-only		Parse options only, don't start any IO
	--output		Write output to file
	--runtime		Runtime in seconds
	--latency-log		Generate per-job latency logs
	--bandwidth-log		Generate per-job bandwidth logs
	--minimal		Minimal (terse) output
	--output-format=type	Output format (terse,json,normal)
	--terse-version=type	Terse version output format (default 3, or 2 or 4).
	--version		Print version info and exit
	--help			Print this page
	--cpuclock-test		Perform test/validation of CPU clock
	--cmdhelp=cmd		Print command help, "all" for all of them
	--enghelp=engine	Print ioengine help, or list available ioengines
	--enghelp=engine,cmd	Print help for an ioengine cmd
	--showcmd		Turn a job file into command line options
	--readonly		Turn on safety read-only checks, preventing
				writes
	--eta=when		When ETA estimate should be printed
				May be "always", "never" or "auto"
	--eta-newline=time	Force a new line for every 'time' period passed
	--section=name		Only run specified section in job file.
				Multiple sections can be specified.
	--alloc-size=kb		Set smalloc pool to this size in kb (def 1024)
	--warnings-fatal	Fio parser warnings are fatal
	--max-jobs		Maximum number of threads/processes to support
	--server=args		Start backend server. See Client/Server section.
	--client=host		Connect to specified backend.
	--idle-prof=option	Report cpu idleness on a system or percpu basis
				(option=system,percpu) or run unit work
				calibration only (option=calibrate).


Any parameters following the options will be assumed to be job files,
unless they match a job file parameter. You can add as many as you want,
each job file will be regarded as a separate group and fio will stonewall
its execution.

The --readonly switch is an extra safety guard to prevent accidentally
turning on a write setting when that is not desired. Fio will only write
if rw=write/randwrite/rw/randrw is given, but this extra safety net can
be used as an extra precaution. It will also enable a write check in the
io engine core to prevent an accidental write due to a fio bug.

The debug switch allows adding options that trigger certain logging
options in fio. Currently the options are:

	process		Dump info related to processes
	file		Dump info related to file actions
	io		Dump info related to IO queuing
	mem		Dump info related to memory allocations
	blktrace	Dump info related to blktrace setup
	verify		Dump info related to IO verification
	all		Enable all debug options
	random		Dump info related to random offset generation
	parse		Dump info related to option matching and parsing
	diskutil	Dump info related to disk utilization updates
	job:x		Dump info only related to job number x
	mutex		Dump info only related to mutex up/down ops
	profile		Dump info related to profile extensions
	time		Dump info related to internal time keeping
	? or help	Show available debug options.

You can specify as many as you want, eg --debug=file,mem will enable
file and memory debugging.

The section switch is meant to make it easier to ship a bigger job file
instead of several smaller ones. Say you define a job file with light,
moderate, and heavy parts. Then you can ask fio to run the given part
only by giving it a --section=heavy command line option. The section
option only applies to job sections, the reserved 'global' section is
always parsed and taken into account.

Fio has an internal allocator for shared memory called smalloc. It
allocates shared structures from this pool. The pool defaults to 1024k
in size, and can grow to 128 pools. If running large jobs with randommap
enabled it can run out of memory, in which case the --alloc-size switch
is handy for starting with a larger pool size. The backing store is
files in /tmp. Fio cleans up after itself, while it is running you
may see .fio_smalloc.* files in /tmp.


Job file
--------

See the HOWTO file for a more detailed description of parameters and what
they mean. This file contains the terse version. You can describe big and
complex setups with the command line, but generally it's a lot easier to
just write a simple job file to describe the workload. The job file format
is in the ini style format, as that is easy to read and write for the user.

The HOWTO or man page has a full list of all options, along with
descriptions, etc. The --cmdhelp option also lists all options. If
used with an option argument, it will detail that particular option.


Client/server
------------

Normally you would run fio as a stand-alone application on the machine
where the IO workload should be generated. However, it is also possible to
run the frontend and backend of fio separately. This makes it possible to
have a fio server running on the machine(s) where the IO workload should
be running, while controlling it from another machine.

To start the server, you would do:

fio --server=args

on that machine, where args defines what fio listens to. The arguments
are of the form 'type,hostname or IP,port'. 'type' is either 'ip' (or ip4)
for TCP/IP v4, 'ip6' for TCP/IP v6, or 'sock' for a local unix domain socket.
'hostname' is either a hostname or IP address, and 'port' is the port to
listen to (only valid for TCP/IP, not a local socket). Some examples:

1) fio --server

   Start a fio server, listening on all interfaces on the default port (8765).

2) fio --server=ip:hostname,4444

   Start a fio server, listening on IP belonging to hostname and on port 4444.

3) fio --server=ip6:::1,4444

   Start a fio server, listening on IPv6 localhost ::1 and on port 4444.

4) fio --server=,4444

   Start a fio server, listening on all interfaces on port 4444.

5) fio --server=1.2.3.4

   Start a fio server, listening on IP 1.2.3.4 on the default port.

6) fio --server=sock:/tmp/fio.sock

   Start a fio server, listening on the local socket /tmp/fio.sock.

When a server is running, you can connect to it from a client. The client
is run with:

fio --local-args --client=server --remote-args <job file(s)>

where --local-args are arguments that are local to the client where it is
running, 'server' is the connect string, and --remote-args and <job file(s)>
are sent to the server. The 'server' string follows the same format as it
does on the server side, to allow IP/hostname/socket and port strings.
You can connect to multiple clients as well, to do that you could run:

fio --client=server2 <job file(s)> --client=server2 <job file(s)>


Platforms
---------

Fio works on (at least) Linux, Solaris, AIX, HP-UX, OSX, NetBSD, Windows
and FreeBSD.  Some features and/or options may only be available on some of
the platforms, typically because those features only apply to that platform
(like the solarisaio engine, or the splice engine on Linux).

Some features are not available on FreeBSD/Solaris even if they could be
implemented, I'd be happy to take patches for that. An example of that is
disk utility statistics and (I think) huge page support, support for that
does exist in FreeBSD/Solaris.

Fio uses pthread mutexes for signalling and locking and FreeBSD does not
support process shared pthread mutexes. As a result, only threads are
supported on FreeBSD. This could be fixed with sysv ipc locking or
other locking alternatives.

Other *BSD platforms are untested, but fio should work there almost out
of the box. Since I don't do test runs or even compiles on those platforms,
your mileage may vary. Sending me patches for other platforms is greatly
appreciated. There's a lot of value in having the same test/benchmark tool
available on all platforms.

Note that POSIX aio is not enabled by default on AIX. If you get messages like:

    Symbol resolution failed for /usr/lib/libc.a(posix_aio.o) because:
        Symbol _posix_kaio_rdwr (number 2) is not exported from dependent module /unix.

you need to enable POSIX aio. Run the following commands as root:

    # lsdev -C -l posix_aio0
        posix_aio0 Defined  Posix Asynchronous I/O
    # cfgmgr -l posix_aio0
    # lsdev -C -l posix_aio0
        posix_aio0 Available  Posix Asynchronous I/O

POSIX aio should work now. To make the change permanent:

    # chdev -l posix_aio0 -P -a autoconfig='available'
        posix_aio0 changed


Author
------

Fio was written by Jens Axboe <axboe@kernel.dk> to enable flexible testing
of the Linux IO subsystem and schedulers. He got tired of writing
specific test applications to simulate a given workload, and found that
the existing io benchmark/test tools out there weren't flexible enough
to do what he wanted.

Jens Axboe <axboe@kernel.dk> 20060905