Parse options only, don't start any I/O.
+.. option:: --merge-blktrace-only
+
+ Merge blktraces only, don't start any I/O.
+
.. option:: --output=filename
Write output to file `filename`.
Force a full status dump of cumulative (from job start) values at `time`
intervals. This option does *not* provide per-period measurements. So
values such as bandwidth are running averages. When the time unit is omitted,
- `time` is interpreted in seconds.
+ `time` is interpreted in seconds. Note that using this option with
+ ``--output-format=json`` will yield output that technically isn't valid
+ json, since the output will be collated sets of valid json. It will need
+ to be split into valid sets of json after the run.
.. option:: --section=name
:option:`zonesize` bytes of data have been transferred. This parameter
must be zero for :option:`zonemode` =zbd.
+.. option:: read_beyond_wp=bool
+
+ This parameter applies to :option:`zonemode` =zbd only.
+
+ Zoned block devices are block devices that consist of multiple zones.
+ Each zone has a type, e.g. conventional or sequential. A conventional
+ zone can be written at any offset that is a multiple of the block
+ size. Sequential zones must be written sequentially. The position at
+ which a write must occur is called the write pointer. A zoned block
+ device can be either drive managed, host managed or host aware. For
+ host managed devices the host must ensure that writes happen
+ sequentially. Fio recognizes host managed devices and serializes
+ writes to sequential zones for these devices.
+
+ If a read occurs in a sequential zone beyond the write pointer then
+ the zoned block device will complete the read without reading any data
+ from the storage medium. Since such reads lead to unrealistically high
+ bandwidth and IOPS numbers fio only reads beyond the write pointer if
+ explicitly told to do so. Default: false.
+
+.. option:: max_open_zones=int
+
+ When running a random write test across an entire drive many more
+ zones will be open than in a typical application workload. Hence this
+ command line option that allows to limit the number of open zones. The
+ number of open zones is defined as the number of zones to which write
+ commands are issued.
+
+.. option:: zone_reset_threshold=float
+
+ A number between zero and one that indicates the ratio of logical
+ blocks with data to the total number of logical blocks in the test
+ above which zones should be reset periodically.
+
+.. option:: zone_reset_frequency=float
+
+ A number between zero and one that indicates how often a zone reset
+ should be issued if the zone reset threshold has been exceeded. A zone
+ reset is submitted after each (1 / zone_reset_frequency) write
+ requests. This and the previous parameter can be used to simulate
+ garbage collection activity.
+
I/O type
~~~~~~~~
will be read at once. If selected true, input from iolog will be read
gradually. Useful when iolog is very large, or it is generated.
+.. option:: merge_blktrace_file=str
+
+ When specified, rather than replaying the logs passed to :option:`read_iolog`,
+ the logs go through a merge phase which aggregates them into a single
+ blktrace. The resulting file is then passed on as the :option:`read_iolog`
+ parameter. The intention here is to make the order of events consistent.
+ This limits the influence of the scheduler compared to replaying multiple
+ blktraces via concurrent jobs.
+
+.. option:: merge_blktrace_scalars=float_list
+
+ This is a percentage based option that is index paired with the list of
+ files passed to :option:`read_iolog`. When merging is performed, scale
+ the time of each event by the corresponding amount. For example,
+ ``--merge_blktrace_scalars="50:100"`` runs the first trace in halftime
+ and the second trace in realtime. This knob is separately tunable from
+ :option:`replay_time_scale` which scales the trace during runtime and
+ does not change the output of the merge unlike this option.
+
+.. option:: merge_blktrace_iters=float_list
+
+ This is a whole number option that is index paired with the list of files
+ passed to :option:`read_iolog`. When merging is performed, run each trace
+ for the specified number of iterations. For example,
+ ``--merge_blktrace_iters="2:1"`` runs the first trace for two iterations
+ and the second trace for one iteration.
+
.. option:: replay_no_stall=bool
When replaying I/O with :option:`read_iolog` the default behavior is to
.. option:: replay_align=int
- Force alignment of I/O offsets and lengths in a trace to this power of 2
- value.
+ Force alignment of the byte offsets in a trace to this value. The value
+ must be a power of 2.
.. option:: replay_scale=int
- Scale sector offsets down by this factor when replaying traces.
+ Scale byte offsets down by this factor when replaying traces. Should most
+ likely use :option:`replay_align` as well.
.. option:: replay_skip=str
data from the rolling collection window. Threshold limits can be expressed
as a fixed value or as a percentage of the mean in the collection window.
+ When using this feature, most jobs should include the :option:`time_based`
+ and :option:`runtime` options or the :option:`loops` option so that fio does not
+ stop running after it has covered the full size of the specified file(s) or device(s).
+
**iops**
Collect IOPS data. Stop the job if all individual IOPS measurements
are within the specified limit of the mean IOPS (e.g., ``iops:2``
**trim**
Trim the given file from the given `offset` for `length` bytes.
+
+I/O Replay - Merging Traces
+---------------------------
+
+Colocation is a common practice used to get the most out of a machine.
+Knowing which workloads play nicely with each other and which ones don't is
+a much harder task. While fio can replay workloads concurrently via multiple
+jobs, it leaves some variability up to the scheduler making results harder to
+reproduce. Merging is a way to make the order of events consistent.
+
+Merging is integrated into I/O replay and done when a
+:option:`merge_blktrace_file` is specified. The list of files passed to
+:option:`read_iolog` go through the merge process and output a single file
+stored to the specified file. The output file is passed on as if it were the
+only file passed to :option:`read_iolog`. An example would look like::
+
+ $ fio --read_iolog="<file1>:<file2>" --merge_blktrace_file="<output_file>"
+
+Creating only the merged file can be done by passing the command line argument
+:option:`merge-blktrace-only`.
+
+Scaling traces can be done to see the relative impact of any particular trace
+being slowed down or sped up. :option:`merge_blktrace_scalars` takes in a colon
+separated list of percentage scalars. It is index paired with the files passed
+to :option:`read_iolog`.
+
+With scaling, it may be desirable to match the running time of all traces.
+This can be done with :option:`merge_blktrace_iters`. It is index paired with
+:option:`read_iolog` just like :option:`merge_blktrace_scalars`.
+
+In an example, given two traces, A and B, each 60s long. If we want to see
+the impact of trace A issuing IOs twice as fast and repeat trace A over the
+runtime of trace B, the following can be done::
+
+ $ fio --read_iolog="<trace_a>:"<trace_b>" --merge_blktrace_file"<output_file>" --merge_blktrace_scalars="50:100" --merge_blktrace_iters="2:1"
+
+This runs trace A at 2x the speed twice for approximately the same runtime as
+a single run of trace B.
+
+
CPU idleness profiling
----------------------
projects / fio.git / blobdiff