简介
fio是IO工具，既可以用于基准测试，也可以用于硬件的压力测试验证（stress/hardware verification）。
支持13种不同的IO引擎(sync、mmap、libaio、posixaio、SG v3、splice、null、network、syslet、guasi、solarisaio或者更多)，IO优先级（支持更新的Linux内核），rate IO，forked or 线程任务等。既适用于块设备，也适用于文件。fio可以解析job描述，这些描述来自于简单可理解的文本格式文件。
fio可以展示多种io性能信息，包括IO延迟(IO latencies)，IO百分率(IO percentiles)。FIO有广泛的应用，例如基准测试、质量测试(QA)、测试验证等。支持Linux、FreeBSD、NetBSD、OS X、Open Solaris、AIX、HPUX以及Windows等操作系统。
fio is an I/O tool meant to be used both for benchmark and stress/hardware verification. It has support for 13 different types of I/O engines (sync, mmap, libaio, posixaio, SG v3, splice, null, network, syslet, guasi, solarisaio, and more), I/O priorities (for newer Linux kernels), rate I/O, forked or threaded jobs, and much more. It can work on block devices as well as files. fio accepts job descriptions in a simple-to-understand text format. Several example job files are included. fio displays all sorts of I/O performance information, including complete IO latencies and percentiles. Fio is in wide use in many places, for both benchmarking, QA, and verification purposes. It supports Linux, FreeBSD, NetBSD, OS X, OpenSolaris, AIX, HP-UX, and Windows.
http://freecode.com/projects/fio
特点
这个工具最大的特点是使用简单，支持的文件操作非常多, 可以覆盖到我们能见到的文件使用方式:
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.
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.
guasi The GUASI I/O engine is the Generic Userspace Asynchronous Syscall Interface approach to asycnronous I/O.
还可以控制io depth对于测试磁盘的性能很有帮助，对结果的解读也做的很明白。
http://blog.yufeng.info/archives/677
帮助
fio-2.1.2 fio [options] [job options] <job file(s)> --debug=options Enable debug logging. May be one/more of: process,file,io,mem,blktrace,verify,random,parse, diskutil,job,mutex,profile,time,net --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=x Output format (terse,json,normal) --terse-version=x Set terse version output format to 'x' --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 --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 --status-interval=t Force full status dump every 't' period passed --readonly Turn on safety read-only checks, preventing writes --section=name Only run specified section in job file --alloc-size=kb Set smalloc pool to this size in kb (def 1024) --warnings-fatal Fio parser warnings are fatal --max-jobs=nr Maximum number of threads/processes to support --server=args Start a backend fio server --daemonize=pidfile Background fio server, write pid to file --client=hostname Talk to remote backend fio server at hostname --idle-prof=option Report cpu idleness on a system or percpu basis (option=system,percpu) or run unit work calibration only (option=calibrate)
例子
[root@localhost data1]# fio --filename=/dev/sda6 --direct=1 --rw=randread --bs=4k --size=60G --numjobs=64 --runtime=10 --group_reporting --name=file2
file2: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=sync, iodepth=1
...
file2: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=sync, iodepth=1
fio-2.1.2
Starting 64 processes
Jobs: 64 (f=64): [rrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrr] [100.0% done] [33816KB/0KB/0KB /s] [8454/0/0 iops] [eta 00m:00s]
file2: (groupid=0, jobs=64): err= 0: pid=5176: Mon Nov 11 11:19:07 2013
read : io=332596KB, bw=33134KB/s, iops=8283, runt= 10038msec
clat (usec): min=61, max=214260, avg=7689.06, stdev=10823.87
lat (usec): min=61, max=214260, avg=7689.46, stdev=10823.87
clat percentiles (usec):
| 1.00th=[ 229], 5.00th=[ 247], 10.00th=[ 262], 20.00th=[ 334],
| 30.00th=[ 1672], 40.00th=[ 2928], 50.00th=[ 4256], 60.00th=[ 5664],
| 70.00th=[ 8160], 80.00th=[11840], 90.00th=[19328], 95.00th=[28032],
| 99.00th=[51968], 99.50th=[63744], 99.90th=[89600], 99.95th=[103936],
| 99.99th=[148480]
bw (KB /s): min= 231, max= 1061, per=1.55%, avg=513.75, stdev=98.50
lat (usec) : 100=0.19%, 250=5.80%, 500=19.22%, 750=1.58%, 1000=0.82%
lat (msec) : 2=4.63%, 4=16.07%, 10=27.74%, 20=14.44%, 50=8.40%
lat (msec) : 100=1.05%, 250=0.06%
cpu : usr=0.11%, sys=0.35%, ctx=83444, majf=0, minf=2203
IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0%
submit : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
complete : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
issued : total=r=83149/w=0/d=0, short=r=0/w=0/d=0
Run status group 0 (all jobs):
READ: io=332596KB, aggrb=33133KB/s, minb=33133KB/s, maxb=33133KB/s, mint=10038msec, maxt=10038msec
Disk stats (read/write):
sda: ios=82814/13, merge=0/6, ticks=636982/30, in_queue=636949, util=98.87%
--filename
（待续）