.BI \-\-parse\-only
Parse options only, don't start any I/O.
.TP
+.BI \-\-merge\-blktrace\-only
+Merge blktraces only, don't start any I/O.
+.TP
.BI \-\-output \fR=\fPfilename
Write output to \fIfilename\fR.
.TP
Force a full status dump of cumulative (from job start) values at \fItime\fR
intervals. This option does *not* provide per-period measurements. So
values such as bandwidth are running averages. When the time unit is omitted,
-\fItime\fR is interpreted in seconds.
+\fItime\fR 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.
.TP
.BI \-\-section \fR=\fPname
Only run specified section \fIname\fR in job file. Multiple sections can be specified.
bytes of data have been transferred. This parameter must be zero for
\fBzonemode\fR=zbd.
+.TP
+.BI read_beyond_wp \fR=\fPbool
+This parameter applies to \fBzonemode=zbd\fR 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.
+.TP
+.BI max_open_zones \fR=\fPint
+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.
+.TP
+.BI zone_reset_threshold \fR=\fPfloat
+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.
+.TP
+.BI zone_reset_frequency \fR=\fPfloat
+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.
+
.SS "I/O type"
.TP
.BI direct \fR=\fPbool
be read at once. If selected true, input from iolog will be read gradually.
Useful when iolog is very large, or it is generated.
.TP
+.BI merge_blktrace_file \fR=\fPstr
+When specified, rather than replaying the logs passed to \fBread_iolog\fR,
+the logs go through a merge phase which aggregates them into a single blktrace.
+The resulting file is then passed on as the \fBread_iolog\fR 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.
+.TP
+.BI merge_blktrace_scalars \fR=\fPfloat_list
+This is a percentage based option that is index paired with the list of files
+passed to \fBread_iolog\fR. 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
+\fBreplay_time_scale\fR which scales the trace during runtime and will not
+change the output of the merge unlike this option.
+.TP
+.BI merge_blktrace_iters \fR=\fPfloat_list
+This is a whole number option that is index paired with the list of files
+passed to \fBread_iolog\fR. 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.
+.TP
.BI replay_no_stall \fR=\fPbool
When replaying I/O with \fBread_iolog\fR the default behavior is to
attempt to respect the timestamps within the log and replay them with the
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.
.RS
+.P
+When using this feature, most jobs should include the \fBtime_based\fR
+and \fBruntime\fR options or the \fBloops\fR option so that fio does not
+stop running after it has covered the full size of the specified file(s)
+or device(s).
+.RS
.RS
.TP
.B iops
Trim the given file from the given `offset' for `length' bytes.
.RE
.RE
+.SH 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.
+.P
+Merging is integrated into I/O replay and done when a \fBmerge_blktrace_file\fR
+is specified. The list of files passed to \fBread_iolog\fR 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 \fBread_iolog\fR. An example would
+look like:
+.RS
+.P
+$ fio \-\-read_iolog="<file1>:<file2>" \-\-merge_blktrace_file="<output_file>"
+.RE
+.P
+Creating only the merged file can be done by passing the command line argument
+\fBmerge-blktrace-only\fR.
+.P
+Scaling traces can be done to see the relative impact of any particular trace
+being slowed down or sped up. \fBmerge_blktrace_scalars\fR takes in a colon
+separated list of percentage scalars. It is index paired with the files passed
+to \fBread_iolog\fR.
+.P
+With scaling, it may be desirable to match the running time of all traces.
+This can be done with \fBmerge_blktrace_iters\fR. It is index paired with
+\fBread_iolog\fR just like \fBmerge_blktrace_scalars\fR.
+.P
+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:
+.RS
+.P
+$ fio \-\-read_iolog="<trace_a>:"<trace_b>" \-\-merge_blktrace_file"<output_file>" \-\-merge_blktrace_scalars="50:100" \-\-merge_blktrace_iters="2:1"
+.RE
+.P
+This runs trace A at 2x the speed twice for approximately the same runtime as
+a single run of trace B.
.SH CPU IDLENESS PROFILING
In some cases, we want to understand CPU overhead in a test. For example, we
test patches for the specific goodness of whether they reduce CPU usage.
projects / fio.git / blobdiff