6. Normal output
7. Terse output
8. Trace file format
+9. CPU idleness profiling
1.0 Overview and history
------------------------
Num threads How many threads or processes should we spread
this workload over.
-
+
The above are the basic parameters defined for a workload, in addition
there's a multitude of parameters that modify other aspects of how this
job behaves.
can specify a number of files by separating the names with a
':' colon. So if you wanted a job to open /dev/sda and /dev/sdb
as the two working files, you would use
- filename=/dev/sda:/dev/sdb. On Windows, disk devices are accessed
- as \\.\PhysicalDrive0 for the first device, \\.\PhysicalDrive1
- for the second etc. If the wanted filename does need to
- include a colon, then escape that with a '\' character.
- For instance, if the filename is "/dev/dsk/foo@3,0:c",
- then you would use filename="/dev/dsk/foo@3,0\:c".
- '-' is a reserved name, meaning stdin or stdout. Which of the
- two depends on the read/write direction set.
+ filename=/dev/sda:/dev/sdb. On Windows, disk devices are
+ accessed as \\.\PhysicalDrive0 for the first device,
+ \\.\PhysicalDrive1 for the second etc. Note: Windows and
+ FreeBSD prevent write access to areas of the disk containing
+ in-use data (e.g. filesystems).
+ If the wanted filename does need to include a colon, then
+ escape that with a '\' character. For instance, if the filename
+ is "/dev/dsk/foo@3,0:c", then you would use
+ filename="/dev/dsk/foo@3,0\:c". '-' is a reserved name, meaning
+ stdin or stdout. Which of the two depends on the read/write
+ direction set.
opendir=str Tell fio to recursively add any file it can find in this
directory and down the file system tree.
ten unit instead, for obvious reasons. Allow values are
1024 or 1000, with 1024 being the default.
+unified_rw_reporting=bool Fio normally reports statistics on a per
+ data direction basis, meaning that read, write, and trim are
+ accounted and reported separately. If this option is set,
+ the fio will sum the results and report them as "mixed"
+ instead.
+
randrepeat=bool For random IO workloads, seed the generator in a predictable
way so that results are repeatable across repetitions.
and is large enough for the specified write phase, nothing
will be done.
-end_fsync=bool If true, fsync file contents when the job exits.
+end_fsync=bool If true, fsync file contents when a write stage has completed.
fsync_on_close=bool If true, fio will fsync() a dirty file on close.
This differs from end_fsync in that it will happen on every
if fio is asked to limit reads or writes to a certain rate.
If that is the case, then the distribution may be skewed.
+random_distribution=str:float By default, fio will use a completely uniform
+ random distribution when asked to perform random IO. Sometimes
+ it is useful to skew the distribution in specific ways,
+ ensuring that some parts of the data is more hot than others.
+ fio includes the following distribution models:
+
+ random Uniform random distribution
+ zipf Zipf distribution
+ pareto Pareto distribution
+
+ When using a zipf or pareto distribution, an input value
+ is also needed to define the access pattern. For zipf, this
+ is the zipf theta. For pareto, it's the pareto power. Fio
+ includes a test program, genzipf, that can be used visualize
+ 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.
+
norandommap Normally fio will cover every block of the file when doing
random IO. If this option is given, fio will just get a
new random offset without looking at past io history. This
will not be as complete as with random maps, this option is
disabled by default.
+random_generator=str Fio supports the following engines for generating
+ IO offsets for random IO:
+
+ tausworthe Strong 2^88 cycle random number generator
+ lfsr Linear feedback shift register generator
+
+ Tausworthe is a strong random number generator, but it
+ requires tracking on the side if we want to ensure that
+ blocks are only read or written once. LFSR guarantees
+ that we never generate the same offset twice, and it's
+ also less computationally expensive. It's not a true
+ random generator, however, though for IO purposes it's
+ typically good enough. LFSR only works with single
+ block sizes, not with workloads that use multiple block
+ sizes. If used with such a workload, fio may read or write
+ some blocks multiple times.
+
nice=int Run the job with the given nice value. See man nice(2).
prio=int Set the io priority value of this job. Linux limits us to
numa_cpu_nodes=str Set this job running on spcified NUMA nodes' CPUs. The
arguments allow comma delimited list of cpu numbers,
A-B ranges, or 'all'. Note, to enable numa options support,
- export the following environment variables,
- export EXTFLAGS+=" -DFIO_HAVE_LIBNUMA "
- export EXTLIBS+=" -lnuma "
+ fio must be built on a system with libnuma-dev(el) installed.
numa_mem_policy=str Set this job's memory policy and corresponding NUMA
nodes. Format of the argements:
less than verify_backlog then not all blocks will be verified,
if verify_backlog_batch is larger than verify_backlog, some
blocks will be verified more than once.
-
+
stonewall
wait_for_previous Wait for preceeding jobs in the job file to exit, before
starting this one. Can be used to insert serialization
for how to capture such logging data. For blktrace replay,
the file needs to be turned into a blkparse binary data
file first (blkparse <device> -o /dev/null -d file_for_fio.bin).
-
+
replay_no_stall=int When replaying I/O with read_iolog the default behavior
is to attempt to respect the time stamps within the log and
replay them with the appropriate delay between IOPS. By
ioscheduler=str Attempt to switch the device hosting the file to the specified
io scheduler before running.
-cpuload=int If the job is a CPU cycle eater, attempt to use the specified
- percentage of CPU cycles.
-
-cpuchunks=int If the job is a CPU cycle eater, split the load into
- cycles of the given time. In microseconds.
-
disk_util=bool Generate disk utilization statistics, if the platform
supports it. Defaults to on.
the values of completion latency below which 99.5% and
99.9% of the observed latencies fell, respectively.
+clocksource=str Use the given clocksource as the base of timing. The
+ supported options are:
+
+ gettimeofday gettimeofday(2)
+
+ clock_gettime clock_gettime(2)
+
+ cpu Internal CPU clock source
+
+ cpu is the preferred clocksource if it is reliable, as it
+ is very fast (and fio is heavy on time calls). Fio will
+ automatically use this clocksource if it's supported and
+ considered reliable on the system it is running on, unless
+ another clocksource is specifically set. For x86/x86-64 CPUs,
+ this means supporting TSC Invariant.
+
gtod_reduce=bool Enable all of the gettimeofday() reducing options
(disable_clat, disable_slat, disable_bw) plus reduce
precision of the timeout somewhat to really shrink
may be symbol ('ENOSPC', 'ENOMEM') or integer.
Example:
ignore_error=EAGAIN,ENOSPC:122
- This option will ignore EAGAIN from READ, and ENOSPC and
- 122(EDQUOT) from WRITE.
+ This option will ignore EAGAIN from READ, and ENOSPC and
+ 122(EDQUOT) from WRITE.
error_dump=bool If set dump every error even if it is non fatal, true
by default. If disabled only fatal error will be dumped
-
+
cgroup=str Add job to this control group. If it doesn't exist, it will
be created. The system must have a mounted cgroup blkio
mount point for this to work. If your system doesn't have it
enabled when polling for a minimum of 0 events (eg when
iodepth_batch_complete=0).
+[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
+ microseconds.
+
[netsplice] hostname=str
[net] hostname=str The host name or IP address to use for TCP or UDP based IO.
If the job is a TCP listener or UDP reader, the hostname is not
[netsplice] port=int
[net] port=int The TCP or UDP port to bind to or connect to.
+[netsplice] nodelay=bool
+[net] nodelay=bool Set TCP_NODELAY on TCP connections.
+
[netsplice] protocol=str
[netsplice] proto=str
[net] protocol=str
[net] listen For TCP network connections, tell fio to listen for incoming
connections rather than initiating an outgoing connection. The
hostname must be omitted if this option is used.
+[net] pingpong Normal a network writer will just continue writing data, and
+ a network reader will just consume packages. If pingpong=1
+ is set, a writer will send its normal payload to the reader,
+ then wait for the reader to send the same payload back. This
+ allows fio to measure network latencies. The submission
+ and completion latencies then measure local time spent
+ sending or receiving, and the completion latency measures
+ how long it took for the other end to receive and send back.
+
[e4defrag] donorname=str
File will be used as a block donor(swap extents between files)
[e4defrag] inplace=int
- Configure donor file blocks allocation strategy
+ Configure donor file blocks allocation strategy
0(default): Preallocate donor's file on init
1 : allocate space immidietly inside defragment event,
and free right after event
Read merges, write merges,
Read ticks, write ticks,
Time spent in queue, disk utilization percentage
- Additional Info (dependant on continue_on_error, default off): total # errors, first error code
-
+ Additional Info (dependant on continue_on_error, default off): total # errors, first error code
+
Additional Info (dependant on description being set): Text description
Completion latency percentiles can be a grouping of up to 20 sets, so
8.0 Trace file format
---------------------
-There are two trace file format that you can encounter. The older (v1) format
+There are two trace file format that you can encounter. The older (v1) format
is unsupported since version 1.20-rc3 (March 2008). It will still be described
below in case that you get an old trace and want to understand it.
The filename is given as an absolute path. The action can be one of these:
add Add the given filename to the trace
-open Open the file with the given filename. The filename has to have
+open Open the file with the given filename. The filename has to have
been added with the add action before.
close Close the file with the given filename. The file has to have been
opened before.
filename action offset length
The filename is given as an absolute path, and has to have been added and opened
-before it can be used with this format. The offset and length are given in
+before it can be used with this format. The offset and length are given in
bytes. The action can be one of these:
wait Wait for 'offset' microseconds. Everything below 100 is discarded.
sync fsync() the file
datasync fdatasync() the file
trim trim the given file from the given 'offset' for 'length' bytes
+
+
+9.0 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.
+fio implements a balloon approach to create a thread per CPU that runs at
+idle priority, meaning that it only runs when nobody else needs the cpu.
+By measuring the amount of work completed by the thread, idleness of each
+CPU can be derived accordingly.
+
+An unit work is defined as touching a full page of unsigned characters. Mean
+and standard deviation of time to complete an unit work is reported in "unit
+work" section. Options can be chosen to report detailed percpu idleness or
+overall system idleness by aggregating percpu stats.
projects / fio.git / blobdiff