.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
Asynchronous read and write using DDN's Infinite Memory Engine (IME). This
engine will try to stack as much IOs as possible by creating requests for IME.
FIO will then decide when to commit these requests.
+.TP
+.B libiscsi
+Read and write iscsi lun with libiscsi.
.SS "I/O engine specific parameters"
In addition, there are some parameters which are only valid when a specific
\fBioengine\fR is in use. These are used identically to normal parameters,
\fBserialize_overlap\fR tells fio to avoid provoking this behavior by explicitly
serializing in-flight I/Os that have a non-zero overlap. Note that setting
this option can reduce both performance and the \fBiodepth\fR achieved.
-Additionally this option does not work when \fBio_submit_mode\fR is set to
-offload. Default: false.
+.RS
+.P
+This option only applies to I/Os issued for a single job except when it is
+enabled along with \fBio_submit_mode\fR=offload. In offload mode, fio
+will check for overlap among all I/Os submitted by offload jobs with \fBserialize_overlap\fR
+enabled.
+.P
+Default: false.
+.RE
.TP
.BI io_submit_mode \fR=\fPstr
This option controls how fio submits the I/O to the I/O engine. The default
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
device accesses.
.TP
.BI replay_align \fR=\fPint
-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.
.TP
.BI replay_scale \fR=\fPint
-Scale sector offsets down by this factor when replaying traces.
+Scale bye offsets down by this factor when replaying traces. Should most
+likely use \fBreplay_align\fR as well.
.SS "Threads, processes and job synchronization"
.TP
.BI replay_skip \fR=\fPstr
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
A description of this job goes here.
.fi
.P
-The job description (if provided) follows on a second line.
+The job description (if provided) follows on a second line for terse v2.
+It appears on the same line for other terse versions.
.P
To enable terse output, use the \fB\-\-minimal\fR or
`\-\-output\-format=terse' command line options. The
.nf
terse_version_3;fio_version;jobname;groupid;error;read_kb;read_bandwidth;read_iops;read_runtime_ms;read_slat_min;read_slat_max;read_slat_mean;read_slat_dev;read_clat_min;read_clat_max;read_clat_mean;read_clat_dev;read_clat_pct01;read_clat_pct02;read_clat_pct03;read_clat_pct04;read_clat_pct05;read_clat_pct06;read_clat_pct07;read_clat_pct08;read_clat_pct09;read_clat_pct10;read_clat_pct11;read_clat_pct12;read_clat_pct13;read_clat_pct14;read_clat_pct15;read_clat_pct16;read_clat_pct17;read_clat_pct18;read_clat_pct19;read_clat_pct20;read_tlat_min;read_lat_max;read_lat_mean;read_lat_dev;read_bw_min;read_bw_max;read_bw_agg_pct;read_bw_mean;read_bw_dev;write_kb;write_bandwidth;write_iops;write_runtime_ms;write_slat_min;write_slat_max;write_slat_mean;write_slat_dev;write_clat_min;write_clat_max;write_clat_mean;write_clat_dev;write_clat_pct01;write_clat_pct02;write_clat_pct03;write_clat_pct04;write_clat_pct05;write_clat_pct06;write_clat_pct07;write_clat_pct08;write_clat_pct09;write_clat_pct10;write_clat_pct11;write_clat_pct12;write_clat_pct13;write_clat_pct14;write_clat_pct15;write_clat_pct16;write_clat_pct17;write_clat_pct18;write_clat_pct19;write_clat_pct20;write_tlat_min;write_lat_max;write_lat_mean;write_lat_dev;write_bw_min;write_bw_max;write_bw_agg_pct;write_bw_mean;write_bw_dev;cpu_user;cpu_sys;cpu_csw;cpu_mjf;cpu_minf;iodepth_1;iodepth_2;iodepth_4;iodepth_8;iodepth_16;iodepth_32;iodepth_64;lat_2us;lat_4us;lat_10us;lat_20us;lat_50us;lat_100us;lat_250us;lat_500us;lat_750us;lat_1000us;lat_2ms;lat_4ms;lat_10ms;lat_20ms;lat_50ms;lat_100ms;lat_250ms;lat_500ms;lat_750ms;lat_1000ms;lat_2000ms;lat_over_2000ms;disk_name;disk_read_iops;disk_write_iops;disk_read_merges;disk_write_merges;disk_read_ticks;write_ticks;disk_queue_time;disk_util
.fi
+.P
+In client/server mode terse output differs from what appears when jobs are run
+locally. Disk utilization data is omitted from the standard terse output and
+for v3 and later appears on its own separate line at the end of each terse
+reporting cycle.
.SH JSON OUTPUT
The \fBjson\fR output format is intended to be both human readable and convenient
for automated parsing. For the most part its sections mirror those of the
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.
/mnt/nfs/fio/192.168.10.121.fileio.tmp
.PD
.RE
+.P
+Terse output in client/server mode will differ slightly from what is produced
+when fio is run in stand-alone mode. See the terse output section for details.
.SH AUTHORS
.B fio
was written by Jens Axboe <axboe@kernel.dk>.
projects / fio.git / blobdiff