7. Terse output
8. Trace file format
9. CPU idleness profiling
+10. Verification and triggers
+11. Log File Formats
+
1.0 Overview and history
------------------------
the next. Multiple files can still be
open depending on 'openfiles'.
- The string can have a number appended, indicating how
- often to switch to a new file. So if option random:4 is
- given, fio will switch to a new random file after 4 ios
- have been issued.
+ zipf Use a zipfian distribution to decide what file
+ to access.
+
+ pareto Use a pareto distribution to decide what file
+ to access.
+
+ gauss Use a gaussian (normal) distribution to decide
+ what file to access.
+
+ For random, roundrobin, and sequential, a postfix can be
+ appended to tell fio how many I/Os to issue before switching
+ to a new file. For example, specifying
+ 'file_service_type=random:8' would cause fio to issue 8 I/Os
+ before selecting a new file at random. For the non-uniform
+ distributions, a floating point postfix can be given to
+ influence how the distribution is skewed. See
+ 'random_distribution' for a description of how that would work.
ioengine=str Defines how the job issues io to the file. The following
types are defined:
overwriting. The writetrim mode works well
for this constraint.
+ pmemblk Read and write through the NVML libpmemblk
+ interface.
+
external Prefix to specify loading an external
IO engine object file. Append the engine
filename, eg ioengine=external:/tmp/foo.o
random Uniform random distribution
zipf Zipf distribution
pareto Pareto distribution
+ gauss Normal (guassian) distribution
+ zoned Zoned random distribution
When using a zipf or pareto distribution, an input value
is also needed to define the access pattern. For zipf, this
what the given input values will yield in terms of hit rates.
If you wanted to use zipf with a theta of 1.2, you would use
random_distribution=zipf:1.2 as the option. If a non-uniform
- model is used, fio will disable use of the random map.
+ model is used, fio will disable use of the random map. For
+ the gauss distribution, a normal deviation is supplied as
+ a value between 0 and 100.
+
+ For a zoned distribution, fio supports specifying percentages
+ of IO access that should fall within what range of the file or
+ device. For example, given a criteria of:
+
+ 60% of accesses should be to the first 10%
+ 30% of accesses should be to the next 20%
+ 8% of accesses should be to to the next 30%
+ 2% of accesses should be to the next 40%
+
+ we can define that through zoning of the random accesses. For
+ the above example, the user would do:
+
+ random_distribution=zoned:60/10:30/20:8/30:2/40
+
+ similarly to how bssplit works for setting ranges and
+ percentages of block sizes. Like bssplit, it's possible to
+ specify separate zones for reads, writes, and trims. If just
+ one set is given, it'll apply to all of them.
percentage_random=int For a random workload, set how big a percentage should
be random. This defaults to 100%, in which case the workload
default is to wait for each job to finish.
bwavgtime=int Average the calculated bandwidth over the given time. Value
- is specified in milliseconds.
+ is specified in milliseconds. If the job also does bandwidth
+ logging through 'write_bw_log', then the minimum of this option
+ and 'log_avg_msec' will be used. Default: 500ms.
iopsavgtime=int Average the calculated IOPS over the given time. Value
- is specified in milliseconds.
+ is specified in milliseconds. If the job also does IOPS logging
+ through 'write_iops_log', then the minimum of this option and
+ 'log_avg_msec' will be used. Default: 500ms.
create_serialize=bool If true, serialize the file creating for the jobs.
This may be handy to avoid interleaving of data
filename. For this option, the suffix is _bw.x.log, where
x is the index of the job (1..N, where N is the number of
jobs). If 'per_job_logs' is false, then the filename will not
- include the job index.
+ include the job index. See 'Log File Formats'.
write_lat_log=str Same as write_bw_log, except that this option stores io
submission, completion, and total latencies instead. If no
and foo_lat.x.log, where x is the index of the job (1..N,
where N is the number of jobs). This helps fio_generate_plot
fine the logs automatically. If 'per_job_logs' is false, then
- the filename will not include the job index.
-
+ the filename will not include the job index. See 'Log File
+ Formats'.
write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is
given with this option, the default filename of
(1..N, where N is the number of jobs). Even if the filename
is given, fio will still append the type of log. If
'per_job_logs' is false, then the filename will not include
- the job index.
+ the job index. See 'Log File Formats'.
log_avg_msec=int By default, fio will log an entry in the iops, latency,
or bw log for every IO that completes. When writing to the
disk log, that can quickly grow to a very large size. Setting
this option makes fio average the each log entry over the
specified period of time, reducing the resolution of the log.
- See log_max as well. Defaults to 0, logging all entries.
+ See log_max_value as well. Defaults to 0, logging all entries.
+
+log_max_value=bool If log_avg_msec is set, fio logs the average over that
+ window. If you instead want to log the maximum value, set this
+ option to 1. Defaults to 0, meaning that averaged values are
+ logged.
-log_max=bool If log_avg_msec is set, fio logs the average over that window.
- If you instead want to log the maximum value, set this option
- to 1. Defaults to 0, meaning that averaged values are logged.
-.
log_offset=int If this is set, the iolog options will include the byte
offset for the IO entry as well as the other data values.
enabled when polling for a minimum of 0 events (eg when
iodepth_batch_complete=0).
+[psyncv2] hipri Set RWF_HIPRI on IO, indicating to the kernel that
+ it's of higher priority than normal.
+
[cpu] cpuload=int Attempt to use the specified percentage of CPU cycles.
[cpu] cpuchunks=int Split the load into cycles of the given time. In
1 : allocate space immidietly inside defragment event,
and free right after event
+[rbd] clustername=str Specifies the name of the Ceph cluster.
+[rbd] rbdname=str Specifies the name of the RBD.
+[rbd] pool=str Specifies the naem of the Ceph pool containing RBD.
+[rbd] clientname=str Specifies the username (without the 'client.' prefix)
+ used to access the Ceph cluster. If the clustername is
+ specified, the clientmae shall be the full type.id
+ string. If no type. prefix is given, fio will add
+ 'client.' by default.
+
[mtd] skip_bad=bool Skip operations against known bad blocks.
[libhdfs] hdfsdirectory libhdfs will create chunk in this HDFS directory
cpu= CPU usage. User and system time, along with the number
of context switches this thread went through, usage of
system and user time, and finally the number of major
- and minor page faults.
+ and minor page faults. The CPU utilization numbers are
+ averages for the jobs in that reporting group, while the
+ context and fault counters are summed.
IO depths= The distribution of io depths over the job life time. The
numbers are divided into powers of 2, so for example the
16= entries includes depths up to that value but higher
For this case, fio would wait for the server to send us the write state,
then execute 'ipmi-reboot server' when that happened.
-10.1 Loading verify state
+10.2 Loading verify state
-------------------------
To load store write state, read verification job file must contain
the verify_state_load option. If that is set, fio will load the previously
stored state. For a local fio run this is done by loading the files directly,
and on a client/server run, the server backend will ask the client to send
the files over and load them from there.
+
+
+11.0 Log File Formats
+---------------------
+
+Fio supports a variety of log file formats, for logging latencies, bandwidth,
+and IOPS. The logs share a common format, which looks like this:
+
+time (msec), value, data direction, offset
+
+Time for the log entry is always in milliseconds. The value logged depends
+on the type of log, it will be one of the following:
+
+ Latency log Value is latency in usecs
+ Bandwidth log Value is in KB/sec
+ IOPS log Value is IOPS
+
+Data direction is one of the following:
+
+ 0 IO is a READ
+ 1 IO is a WRITE
+ 2 IO is a TRIM
+
+The offset is the offset, in bytes, from the start of the file, for that
+particular IO. The logging of the offset can be toggled with 'log_offset'.
+
+If windowed logging is enabled though 'log_avg_msec', then fio doesn't log
+individual IOs. Instead of logs the average values over the specified
+period of time. Since 'data direction' and 'offset' are per-IO values,
+they aren't applicable if windowed logging is enabled. If windowed logging
+is enabled and 'log_max_value' is set, then fio logs maximum values in
+that window instead of averages.
+
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