8. Trace file format
9. CPU idleness profiling
10. Verification and triggers
+11. Log File Formats
+
1.0 Overview and history
------------------------
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
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
is fully random. It can be set from anywhere from 0 to 100.
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
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
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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