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Jens Axboeebac4652005-12-08 15:25:21 +01001fio
2---
3
4fio is a tool that will spawn a number of thread doing a particular
5type of io action as specified by the user. fio takes a number of
6global parameters, each inherited by the thread unless otherwise
7parameters given to them overriding that setting is given.
8
Jens Axboe2b02b542005-12-08 15:29:14 +01009
10Source
11------
12
13fio resides in a git repo, the canonical place is:
14
15git://brick.kernel.dk/data/git/fio.git
16
17Snapshots are frequently generated as well and they include the git
18meta data as well. You can download them here:
19
20http://brick.kernel.dk/snaps/
21
Jens Axboe1053a102006-06-06 09:23:13 +020022Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository, you
23can find them here:
24
25http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio
26
Jens Axboe2b02b542005-12-08 15:29:14 +010027
Jens Axboebbfd6b02006-06-07 19:42:54 +020028Building
29--------
30
31Just type 'make' and 'make install'. If on FreeBSD, for now you have to
32specify the FreeBSD Makefile with -f, eg:
33
34$ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install
35
Jens Axboeedffcb92006-06-08 13:40:18 +020036Likewise with OpenSolaris, use the Makefile.solaris to compile there.
Jens Axboebbfd6b02006-06-07 19:42:54 +020037This might change in the future if I opt for an autoconf type setup.
38
39
Jens Axboeebac4652005-12-08 15:25:21 +010040Options
41-------
42
43$ fio
44 -s IO is sequential
45 -b block size in KiB for each io
46 -t <sec> Runtime in seconds
47 -r For random io, sequence must be repeatable
48 -R <on> If one thread fails to meet rate, quit all
49 -o <on> Use direct IO is 1, buffered if 0
50 -l Generate per-job latency logs
51 -w Generate per-job bandwidth logs
52 -f <file> Read <file> for job descriptions
Jens Axboe4785f992006-05-26 03:59:10 +020053 -h Print help info
Jens Axboeebac4652005-12-08 15:25:21 +010054 -v Print version information and exit
55
56The <jobs> format is as follows:
57
Jens Axboe01452052006-06-07 10:29:47 +020058 name=x Use 'x' as the identifier for this job.
Jens Axboeebac4652005-12-08 15:25:21 +010059 directory=x Use 'x' as the top level directory for storing files
Jens Axboe3d60d1e2006-05-25 06:31:06 +020060 rw=x 'x' may be: read, randread, write, randwrite,
61 rw (read-write mix), randrw (read-write random mix)
Jens Axboea6ccc7b2006-06-02 10:14:15 +020062 rwmixcycle=x Base cycle for switching between read and write
63 in msecs.
64 rwmixread=x 'x' percentage of rw mix ios will be reads. If
65 rwmixwrite is also given, the last of the two will
66 be used if they don't add up to 100%.
67 rwmixwrite=x 'x' percentage of rw mix ios will be writes. See
68 rwmixread.
Jens Axboeebac4652005-12-08 15:25:21 +010069 size=x Set file size to x bytes (x string can include k/m/g)
70 ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio,
71 posixaio for POSIX aio, sync for regular read/write io,
Jens Axboe8756e4d2006-05-27 20:24:53 +020072 mmap for mmap'ed io, splice for using splice/vmsplice,
73 or sgio for direct SG_IO io. The latter only works on
74 Linux on SCSI (or SCSI-like devices, such as
75 usb-storage or sata/libata driven) devices.
Jens Axboeebac4652005-12-08 15:25:21 +010076 iodepth=x For async io, allow 'x' ios in flight
77 overwrite=x If 'x', layout a write file first.
78 prio=x Run io at prio X, 0-7 is the kernel allowed range
79 prioclass=x Run io at prio class X
80 bs=x Use 'x' for thread blocksize. May include k/m postfix.
81 bsrange=x-y Mix thread block sizes randomly between x and y. May
82 also include k/m postfix.
83 direct=x 1 for direct IO, 0 for buffered IO
84 thinktime=x "Think" x usec after each io
85 rate=x Throttle rate to x KiB/sec
86 ratemin=x Quit if rate of x KiB/sec can't be met
87 ratecycle=x ratemin averaged over x msecs
88 cpumask=x Only allow job to run on CPUs defined by mask.
89 fsync=x If writing, fsync after every x blocks have been written
90 startdelay=x Start this thread x seconds after startup
91 timeout=x Terminate x seconds after startup
92 offset=x Start io at offset x (x string can include k/m/g)
93 invalidate=x Invalidate page cache for file prior to doing io
94 sync=x Use sync writes if x and writing
95 mem=x If x == malloc, use malloc for buffers. If x == shm,
96 use shm for buffers. If x == mmap, use anon mmap.
97 exitall When one thread quits, terminate the others
98 bwavgtime=x Average bandwidth stats over an x msec window.
99 create_serialize=x If 'x', serialize file creation.
100 create_fsync=x If 'x', run fsync() after file creation.
Jens Axboefc1a4712006-05-30 13:04:05 +0200101 end_fsync=x If 'x', run fsync() after end-of-job.
Jens Axboeebac4652005-12-08 15:25:21 +0100102 loops=x Run the job 'x' number of times.
103 verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32,
104 use crc32 for verifies. md5 is 'safer', but crc32 is
105 a lot faster. Only makes sense for writing to a file.
106 stonewall Wait for preceeding jobs to end before running.
107 numjobs=x Create 'x' similar entries for this job
108 thread Use pthreads instead of forked jobs
Jens Axboe20dc95c2005-12-09 10:29:35 +0100109 zonesize=x
110 zoneskip=y Zone options must be paired. If given, the job
111 will skip y bytes for every x read/written. This
112 can be used to gauge hard drive speed over the entire
113 platter, without reading everything. Both x/y can
114 include k/m/g suffix.
Jens Axboeaea47d42006-05-26 19:27:29 +0200115 iolog=x Open and read io pattern from file 'x'. The file must
116 contain one io action per line in the following format:
117 rw, offset, length
118 where with rw=0/1 for read/write, and the offset
119 and length entries being in bytes.
Jens Axboe843a7412006-06-01 21:14:21 -0700120 write_iolog=x Write an iolog to file 'x' in the same format as iolog.
121 The iolog options are exclusive, if both given the
122 read iolog will be performed.
Jens Axboec04f7ec2006-05-31 10:13:16 +0200123 lockmem=x Lock down x amount of memory on the machine, to
124 simulate a machine with less memory available. x can
125 include k/m/g suffix.
Jens Axboeb6f4d882006-06-02 10:32:51 +0200126 nice=x Run job at given nice value.
Jens Axboe4e0ba8a2006-06-06 09:36:28 +0200127 exec_prerun=x Run 'x' before job io is begun.
128 exec_postrun=x Run 'x' after job io has finished.
Jens Axboeda867742006-06-06 10:39:10 -0700129 ioscheduler=x Use ioscheduler 'x' for this job.
Jens Axboeebac4652005-12-08 15:25:21 +0100130
131Examples using a job file
132-------------------------
133
134A sample job file doing the same as above would look like this:
135
136[read_file]
137rw=0
138bs=4096
139
140[write_file]
141rw=1
142bs=16384
143
144And fio would be invoked as:
145
146$ fio -o1 -s -f file_with_above
147
148The second example would look like this:
149
150[rf1]
151rw=0
152prio=6
153
154[rf2]
155rw=0
156prio=3
157
158[rf3]
159rw=0
160prio=0
161direct=1
162
163And fio would be invoked as:
164
165$ fio -o0 -s -b4096 -f file_with_above
166
167'global' is a reserved keyword. When used as the filename, it sets the
168default options for the threads following that section. It is possible
169to have more than one global section in the file, as it only affects
170subsequent jobs.
171
172Also see the examples/ dir for sample job files.
173
174
175Interpreting the output
176-----------------------
177
178fio spits out a lot of output. While running, fio will display the
179status of the jobs created. An example of that would be:
180
181Threads now running: 2 : [ww] [5.73% done]
182
183The characters inside the square brackets denote the current status of
184each thread. The possible values (in typical life cycle order) are:
185
186Idle Run
187---- ---
188P Thread setup, but not started.
189C Thread created and running, but not doing anything yet
190 R Running, doing sequential reads.
191 r Running, doing random reads.
192 W Running, doing sequential writes.
193 w Running, doing random writes.
194V Running, doing verification of written data.
195E Thread exited, not reaped by main thread yet.
196_ Thread reaped.
197
198The other values are fairly self explanatory - number of thread currently
199running and doing io, and the estimated completion percentage.
200
201When fio is done (or interrupted by ctrl-c), it will show the data for
202each thread, group of threads, and disks in that order. For each data
203direction, the output looks like:
204
205Client1 (g=0): err= 0:
206 write: io= 32MiB, bw= 666KiB/s, runt= 50320msec
207 slat (msec): min= 0, max= 136, avg= 0.03, dev= 1.92
208 clat (msec): min= 0, max= 631, avg=48.50, dev=86.82
209 bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, dev=681.68
210 cpu : usr=1.49%, sys=0.25%, ctx=7969
211
212The client number is printed, along with the group id and error of that
213thread. Below is the io statistics, here for writes. In the order listed,
214they denote:
215
216io= Number of megabytes io performed
217bw= Average bandwidth rate
218runt= The runtime of that thread
219 slat= Submission latency (avg being the average, dev being the
220 standard deviation). This is the time it took to submit
221 the io. For sync io, the slat is really the completion
222 latency, since queue/complete is one operation there.
223 clat= Completion latency. Same names as slat, this denotes the
224 time from submission to completion of the io pieces. For
225 sync io, clat will usually be equal (or very close) to 0,
226 as the time from submit to complete is basically just
227 CPU time (io has already been done, see slat explanation).
228 bw= Bandwidth. Same names as the xlat stats, but also includes
229 an approximate percentage of total aggregate bandwidth
230 this thread received in this group. This last value is
231 only really useful if the threads in this group are on the
232 same disk, since they are then competing for disk access.
233cpu= CPU usage. User and system time, along with the number
234 of context switches this thread went through.
235
236After each client has been listed, the group statistics are printed. They
237will look like this:
238
239Run status group 0 (all jobs):
240 READ: io=64MiB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec
241 WRITE: io=64MiB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec
242
243For each data direction, it prints:
244
245io= Number of megabytes io performed.
246aggrb= Aggregate bandwidth of threads in this group.
247minb= The minimum average bandwidth a thread saw.
248maxb= The maximum average bandwidth a thread saw.
249mint= The minimum runtime of a thread.
250maxt= The maximum runtime of a thread.
251
252And finally, the disk statistics are printed. They will look like this:
253
254Disk stats (read/write):
255 sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00%
256
257Each value is printed for both reads and writes, with reads first. The
258numbers denote:
259
260ios= Number of ios performed by all groups.
261merge= Number of merges io the io scheduler.
262ticks= Number of ticks we kept the disk busy.
263io_queue= Total time spent in the disk queue.
264util= The disk utilization. A value of 100% means we kept the disk
265 busy constantly, 50% would be a disk idling half of the time.