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ebac4655 JA |
1 | fio |
2 | --- | |
3 | ||
79809113 JA |
4 | fio is a tool that will spawn a number of threads or processes doing a |
5 | particular type of io action as specified by the user. fio takes a | |
6 | number of global parameters, each inherited by the thread unless | |
7 | otherwise parameters given to them overriding that setting is given. | |
8 | The typical use of fio is to write a job file matching the io load | |
9 | one wants to simulate. | |
ebac4655 | 10 | |
2b02b546 JA |
11 | |
12 | Source | |
13 | ------ | |
14 | ||
15 | fio resides in a git repo, the canonical place is: | |
16 | ||
17 | git://brick.kernel.dk/data/git/fio.git | |
18 | ||
79809113 JA |
19 | Snapshots are frequently generated and they include the git meta data as |
20 | well. You can download them here: | |
2b02b546 JA |
21 | |
22 | http://brick.kernel.dk/snaps/ | |
23 | ||
1053a106 JA |
24 | Pascal Bleser <guru@unixtech.be> has fio RPMs in his repository, you |
25 | can find them here: | |
26 | ||
27 | http://linux01.gwdg.de/~pbleser/rpm-navigation.php?cat=System/fio | |
28 | ||
2b02b546 | 29 | |
bbfd6b00 JA |
30 | Building |
31 | -------- | |
32 | ||
33 | Just type 'make' and 'make install'. If on FreeBSD, for now you have to | |
34 | specify the FreeBSD Makefile with -f, eg: | |
35 | ||
36 | $ make -f Makefile.Freebsd && make -f Makefile.FreeBSD install | |
37 | ||
edffcb96 | 38 | Likewise with OpenSolaris, use the Makefile.solaris to compile there. |
bbfd6b00 JA |
39 | This might change in the future if I opt for an autoconf type setup. |
40 | ||
41 | ||
ebac4655 JA |
42 | Options |
43 | ------- | |
44 | ||
45 | $ fio | |
46 | -s IO is sequential | |
47 | -b block size in KiB for each io | |
48 | -t <sec> Runtime in seconds | |
49 | -r For random io, sequence must be repeatable | |
50 | -R <on> If one thread fails to meet rate, quit all | |
51 | -o <on> Use direct IO is 1, buffered if 0 | |
52 | -l Generate per-job latency logs | |
53 | -w Generate per-job bandwidth logs | |
54 | -f <file> Read <file> for job descriptions | |
eb8bbf48 | 55 | -O <file> Log output to file |
4785f995 | 56 | -h Print help info |
ebac4655 JA |
57 | -v Print version information and exit |
58 | ||
79809113 JA |
59 | |
60 | Job file | |
61 | -------- | |
62 | ||
63 | Only a few options can be controlled with command line parameters, | |
64 | generally it's a lot easier to just write a simple job file to describe | |
65 | the workload. The job file format is in the ini style format, as it's | |
66 | easy to read and write for the user. | |
67 | ||
68 | The job file parameters are: | |
ebac4655 | 69 | |
01452055 | 70 | name=x Use 'x' as the identifier for this job. |
ebac4655 | 71 | directory=x Use 'x' as the top level directory for storing files |
3d60d1ed JA |
72 | rw=x 'x' may be: read, randread, write, randwrite, |
73 | rw (read-write mix), randrw (read-write random mix) | |
a6ccc7be JA |
74 | rwmixcycle=x Base cycle for switching between read and write |
75 | in msecs. | |
76 | rwmixread=x 'x' percentage of rw mix ios will be reads. If | |
77 | rwmixwrite is also given, the last of the two will | |
78 | be used if they don't add up to 100%. | |
79 | rwmixwrite=x 'x' percentage of rw mix ios will be writes. See | |
80 | rwmixread. | |
ebac4655 JA |
81 | size=x Set file size to x bytes (x string can include k/m/g) |
82 | ioengine=x 'x' may be: aio/libaio/linuxaio for Linux aio, | |
83 | posixaio for POSIX aio, sync for regular read/write io, | |
8756e4d4 JA |
84 | mmap for mmap'ed io, splice for using splice/vmsplice, |
85 | or sgio for direct SG_IO io. The latter only works on | |
86 | Linux on SCSI (or SCSI-like devices, such as | |
87 | usb-storage or sata/libata driven) devices. | |
ebac4655 JA |
88 | iodepth=x For async io, allow 'x' ios in flight |
89 | overwrite=x If 'x', layout a write file first. | |
90 | prio=x Run io at prio X, 0-7 is the kernel allowed range | |
91 | prioclass=x Run io at prio class X | |
92 | bs=x Use 'x' for thread blocksize. May include k/m postfix. | |
93 | bsrange=x-y Mix thread block sizes randomly between x and y. May | |
94 | also include k/m postfix. | |
95 | direct=x 1 for direct IO, 0 for buffered IO | |
96 | thinktime=x "Think" x usec after each io | |
97 | rate=x Throttle rate to x KiB/sec | |
98 | ratemin=x Quit if rate of x KiB/sec can't be met | |
99 | ratecycle=x ratemin averaged over x msecs | |
100 | cpumask=x Only allow job to run on CPUs defined by mask. | |
101 | fsync=x If writing, fsync after every x blocks have been written | |
102 | startdelay=x Start this thread x seconds after startup | |
103 | timeout=x Terminate x seconds after startup | |
104 | offset=x Start io at offset x (x string can include k/m/g) | |
105 | invalidate=x Invalidate page cache for file prior to doing io | |
106 | sync=x Use sync writes if x and writing | |
107 | mem=x If x == malloc, use malloc for buffers. If x == shm, | |
108 | use shm for buffers. If x == mmap, use anon mmap. | |
109 | exitall When one thread quits, terminate the others | |
110 | bwavgtime=x Average bandwidth stats over an x msec window. | |
111 | create_serialize=x If 'x', serialize file creation. | |
112 | create_fsync=x If 'x', run fsync() after file creation. | |
fc1a4713 | 113 | end_fsync=x If 'x', run fsync() after end-of-job. |
ebac4655 JA |
114 | loops=x Run the job 'x' number of times. |
115 | verify=x If 'x' == md5, use md5 for verifies. If 'x' == crc32, | |
116 | use crc32 for verifies. md5 is 'safer', but crc32 is | |
117 | a lot faster. Only makes sense for writing to a file. | |
118 | stonewall Wait for preceeding jobs to end before running. | |
119 | numjobs=x Create 'x' similar entries for this job | |
120 | thread Use pthreads instead of forked jobs | |
20dc95c4 JA |
121 | zonesize=x |
122 | zoneskip=y Zone options must be paired. If given, the job | |
123 | will skip y bytes for every x read/written. This | |
124 | can be used to gauge hard drive speed over the entire | |
125 | platter, without reading everything. Both x/y can | |
126 | include k/m/g suffix. | |
aea47d44 JA |
127 | iolog=x Open and read io pattern from file 'x'. The file must |
128 | contain one io action per line in the following format: | |
129 | rw, offset, length | |
130 | where with rw=0/1 for read/write, and the offset | |
131 | and length entries being in bytes. | |
843a7413 JA |
132 | write_iolog=x Write an iolog to file 'x' in the same format as iolog. |
133 | The iolog options are exclusive, if both given the | |
134 | read iolog will be performed. | |
c04f7ec3 JA |
135 | lockmem=x Lock down x amount of memory on the machine, to |
136 | simulate a machine with less memory available. x can | |
137 | include k/m/g suffix. | |
b6f4d880 | 138 | nice=x Run job at given nice value. |
4e0ba8af JA |
139 | exec_prerun=x Run 'x' before job io is begun. |
140 | exec_postrun=x Run 'x' after job io has finished. | |
da86774e | 141 | ioscheduler=x Use ioscheduler 'x' for this job. |
ebac4655 | 142 | |
79809113 | 143 | |
ebac4655 JA |
144 | Examples using a job file |
145 | ------------------------- | |
146 | ||
79809113 | 147 | Example 1) Two random readers |
ebac4655 | 148 | |
79809113 JA |
149 | Lets say we want to simulate two threads reading randomly from a file |
150 | each. They will be doing IO in 4KiB chunks, using raw (O_DIRECT) IO. | |
151 | Since they share most parameters, we'll put those in the [global] | |
152 | section. Job 1 will use a 128MiB file, job 2 will use a 256MiB file. | |
ebac4655 | 153 | |
79809113 | 154 | ; ---snip--- |
ebac4655 | 155 | |
79809113 JA |
156 | [global] |
157 | ioengine=sync ; regular read/write(2), the default | |
158 | rw=randread | |
159 | bs=4k | |
160 | direct=1 | |
ebac4655 | 161 | |
79809113 JA |
162 | [file1] |
163 | size=128m | |
ebac4655 | 164 | |
79809113 JA |
165 | [file2] |
166 | size=256m | |
ebac4655 | 167 | |
79809113 | 168 | ; ---snip--- |
ebac4655 | 169 | |
79809113 JA |
170 | Generally the [] bracketed name specifies a file name, but the "global" |
171 | keyword is reserved for setting options that are inherited by each | |
172 | subsequent job description. It's possible to have several [global] | |
173 | sections in the job file, each one adds options that are inherited by | |
174 | jobs defined below it. The name can also point to a block device, such | |
175 | as /dev/sda. To run the above job file, simply do: | |
ebac4655 | 176 | |
79809113 JA |
177 | $ fio jobfile |
178 | ||
179 | Example 2) Many random writers | |
180 | ||
181 | Say we want to exercise the IO subsystem some more. We'll define 64 | |
182 | threads doing random buffered writes. We'll let each thread use async io | |
183 | with a depth of 4 ios in flight. A job file would then look like this: | |
ebac4655 | 184 | |
79809113 | 185 | ; ---snip--- |
ebac4655 | 186 | |
79809113 JA |
187 | [global] |
188 | ioengine=libaio | |
189 | iodepth=4 | |
190 | rw=randwrite | |
191 | bs=32k | |
192 | direct=0 | |
193 | size=64m | |
ebac4655 | 194 | |
79809113 JA |
195 | [files] |
196 | numjobs=64 | |
ebac4655 | 197 | |
79809113 JA |
198 | ; ---snip--- |
199 | ||
200 | This will create files.[0-63] and perform the random writes to them. | |
201 | ||
202 | There are endless ways to define jobs, the examples/ directory contains | |
203 | a few more examples. | |
ebac4655 JA |
204 | |
205 | ||
206 | Interpreting the output | |
207 | ----------------------- | |
208 | ||
209 | fio spits out a lot of output. While running, fio will display the | |
210 | status of the jobs created. An example of that would be: | |
211 | ||
212 | Threads now running: 2 : [ww] [5.73% done] | |
213 | ||
214 | The characters inside the square brackets denote the current status of | |
215 | each thread. The possible values (in typical life cycle order) are: | |
216 | ||
217 | Idle Run | |
218 | ---- --- | |
219 | P Thread setup, but not started. | |
79809113 JA |
220 | C Thread created. |
221 | I Thread initialized, waiting. | |
ebac4655 JA |
222 | R Running, doing sequential reads. |
223 | r Running, doing random reads. | |
224 | W Running, doing sequential writes. | |
225 | w Running, doing random writes. | |
79809113 JA |
226 | M Running, doing mixed sequential reads/writes. |
227 | m Running, doing mixed random reads/writes. | |
228 | F Running, currently waiting for fsync() | |
ebac4655 JA |
229 | V Running, doing verification of written data. |
230 | E Thread exited, not reaped by main thread yet. | |
231 | _ Thread reaped. | |
232 | ||
79809113 JA |
233 | The other values are fairly self explanatory - number of threads |
234 | currently running and doing io, and the estimated completion percentage | |
235 | and time. | |
ebac4655 JA |
236 | |
237 | When fio is done (or interrupted by ctrl-c), it will show the data for | |
238 | each thread, group of threads, and disks in that order. For each data | |
239 | direction, the output looks like: | |
240 | ||
241 | Client1 (g=0): err= 0: | |
242 | write: io= 32MiB, bw= 666KiB/s, runt= 50320msec | |
243 | slat (msec): min= 0, max= 136, avg= 0.03, dev= 1.92 | |
244 | clat (msec): min= 0, max= 631, avg=48.50, dev=86.82 | |
245 | bw (KiB/s) : min= 0, max= 1196, per=51.00%, avg=664.02, dev=681.68 | |
246 | cpu : usr=1.49%, sys=0.25%, ctx=7969 | |
247 | ||
248 | The client number is printed, along with the group id and error of that | |
249 | thread. Below is the io statistics, here for writes. In the order listed, | |
250 | they denote: | |
251 | ||
252 | io= Number of megabytes io performed | |
253 | bw= Average bandwidth rate | |
254 | runt= The runtime of that thread | |
255 | slat= Submission latency (avg being the average, dev being the | |
256 | standard deviation). This is the time it took to submit | |
257 | the io. For sync io, the slat is really the completion | |
258 | latency, since queue/complete is one operation there. | |
259 | clat= Completion latency. Same names as slat, this denotes the | |
260 | time from submission to completion of the io pieces. For | |
261 | sync io, clat will usually be equal (or very close) to 0, | |
262 | as the time from submit to complete is basically just | |
263 | CPU time (io has already been done, see slat explanation). | |
264 | bw= Bandwidth. Same names as the xlat stats, but also includes | |
265 | an approximate percentage of total aggregate bandwidth | |
266 | this thread received in this group. This last value is | |
267 | only really useful if the threads in this group are on the | |
268 | same disk, since they are then competing for disk access. | |
269 | cpu= CPU usage. User and system time, along with the number | |
270 | of context switches this thread went through. | |
271 | ||
272 | After each client has been listed, the group statistics are printed. They | |
273 | will look like this: | |
274 | ||
275 | Run status group 0 (all jobs): | |
276 | READ: io=64MiB, aggrb=22178, minb=11355, maxb=11814, mint=2840msec, maxt=2955msec | |
277 | WRITE: io=64MiB, aggrb=1302, minb=666, maxb=669, mint=50093msec, maxt=50320msec | |
278 | ||
279 | For each data direction, it prints: | |
280 | ||
281 | io= Number of megabytes io performed. | |
282 | aggrb= Aggregate bandwidth of threads in this group. | |
283 | minb= The minimum average bandwidth a thread saw. | |
284 | maxb= The maximum average bandwidth a thread saw. | |
79809113 JA |
285 | mint= The smallest runtime of the threads in that group. |
286 | maxt= The longest runtime of the threads in that group. | |
ebac4655 JA |
287 | |
288 | And finally, the disk statistics are printed. They will look like this: | |
289 | ||
290 | Disk stats (read/write): | |
291 | sda: ios=16398/16511, merge=30/162, ticks=6853/819634, in_queue=826487, util=100.00% | |
292 | ||
293 | Each value is printed for both reads and writes, with reads first. The | |
294 | numbers denote: | |
295 | ||
296 | ios= Number of ios performed by all groups. | |
297 | merge= Number of merges io the io scheduler. | |
298 | ticks= Number of ticks we kept the disk busy. | |
299 | io_queue= Total time spent in the disk queue. | |
300 | util= The disk utilization. A value of 100% means we kept the disk | |
301 | busy constantly, 50% would be a disk idling half of the time. | |
79809113 JA |
302 | |
303 | ||
304 | Author | |
305 | ------ | |
306 | ||
307 | Fio was written by Jens Axboe <axboe@suse.de> to enable flexible testing | |
308 | of the Linux IO subsystem and schedulers. He got tired of writing | |
309 | specific test applications to simulate a given workload, and found that | |
310 | the existing io benchmark/test tools out there weren't flexible enough | |
311 | to do what he wanted. | |
312 | ||
313 | Jens Axboe <axboe@suse.de> 20060609 | |
314 |