defines engine specific options.
libhdfs Read and write through Hadoop (HDFS).
- The 'filename' option is used to specify host,
- port of the hdfs name-node to connect. This
- engine interprets offsets a little
+ This engine interprets offsets a little
differently. In HDFS, files once created
cannot be modified. So random writes are not
possible. To imitate this, libhdfs engine
- expects bunch of small files to be created
- over HDFS, and engine will randomly pick a
- file out of those files based on the offset
- generated by fio backend. (see the example
- job file to create such files, use rw=write
- option). Please note, you might want to set
- necessary environment variables to work with
- hdfs/libhdfs properly.
+ creates bunch of small files, and engine will
+ pick a file out of those files based on the
+ offset enerated by fio backend. Each jobs uses
+ it's own connection to HDFS.
mtd Read, write and erase an MTD character device
(e.g., /dev/mtd0). Discards are treated as
iodepth_batch=int This defines how many pieces of IO to submit at once.
It defaults to 1 which means that we submit each IO
as soon as it is available, but can be raised to submit
- bigger batches of IO at the time.
+ bigger batches of IO at the time. If it is set to 0 the iodepth
+ value will be used.
+iodepth_batch_complete_min=int
iodepth_batch_complete=int This defines how many pieces of IO to retrieve
at once. It defaults to 1 which means that we'll ask
for a minimum of 1 IO in the retrieval process from
events before queuing more IO. This helps reduce
IO latency, at the cost of more retrieval system calls.
+iodepth_batch_complete_max=int This defines maximum pieces of IO to
+ retrieve at once. This variable should be used along with
+ iodepth_batch_complete_min=int variable, specifying the range
+ of min and max amount of IO which should be retrieved. By default
+ it is equal to iodepth_batch_complete_min value.
+
+ Example #1:
+
+ iodepth_batch_complete_min=1
+ iodepth_batch_complete_max=<iodepth>
+
+ which means that we will retrieve at leat 1 IO and up to the
+ whole submitted queue depth. If none of IO has been completed
+ yet, we will wait.
+
+ Example #2:
+
+ iodepth_batch_complete_min=0
+ iodepth_batch_complete_max=<iodepth>
+
+ which means that we can retrieve up to the whole submitted
+ queue depth, but if none of IO has been completed yet, we will
+ NOT wait and immediately exit the system call. In this example
+ we simply do polling.
+
iodepth_low=int The low water mark indicating when to start filling
the queue again. Defaults to the same as iodepth, meaning
that fio will attempt to keep the queue full at all times.
will only limit writes (to 500KB/sec), the latter will only
limit reads.
-ratemin=int Tell fio to do whatever it can to maintain at least this
+rate_min=int Tell fio to do whatever it can to maintain at least this
bandwidth. Failing to meet this requirement, will cause
the job to exit. The same format as rate is used for
read vs write separation.
the job to exit. The same format as rate is used for read vs
write separation.
+rate_process=str This option controls how fio manages rated IO
+ submissions. The default is 'linear', which submits IO in a
+ linear fashion with fixed delays between IOs that gets
+ adjusted based on IO completion rates. If this is set to
+ 'poisson', fio will submit IO based on a more real world
+ random request flow, known as the Poisson process
+ (https://en.wikipedia.org/wiki/Poisson_process). The lambda
+ will be 10^6 / IOPS for the given workload.
+
latency_target=int If set, fio will attempt to find the max performance
point that the given workload will run at while maintaining a
latency below this target. The values is given in microseconds.
max_latency=int If set, fio will exit the job if it exceeds this maximum
latency. It will exit with an ETIME error.
-ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number
+rate_cycle=int Average bandwidth for 'rate' and 'rate_min' over this number
of milliseconds.
cpumask=int Set the CPU affinity of this job. The parameter given is a
backing. Append filename after mmaphuge, ala
mem=mmaphuge:/hugetlbfs/file
+ mmapshared Same as mmap, but use a MMAP_SHARED
+ mapping.
+
The area allocated is a function of the maximum allowed
bs size for the job, multiplied by the io depth given. Note
that for shmhuge and mmaphuge to work, the system must have
to wait for each job to finish, sometimes that is not the
desired action.
+exitall_on_error When one job finishes in error, terminate the rest. The
+ default is to wait for each job to finish.
+
bwavgtime=int Average the calculated bandwidth over the given time. Value
is specified in milliseconds.
in the specified log file. This feature depends on the
availability of zlib.
-log_store_compressed=bool If set, and log_compression is also set,
- fio will store the log files in a compressed format. They
- can be decompressed with fio, using the --inflate-log
- command line parameter. The files will be stored with a
- .fz suffix.
+log_compression_cpus=str Define the set of CPUs that are allowed to
+ handle online log compression for the IO jobs. This can
+ provide better isolation between performance sensitive jobs,
+ and background compression work.
+
+log_store_compressed=bool If set, fio will store the log files in a
+ compressed format. They can be decompressed with fio, using
+ the --inflate-log command line parameter. The files will be
+ stored with a .fz suffix.
block_error_percentiles=bool If set, record errors in trim block-sized
units from writes and trims and output a histogram of
If the job is a TCP listener or UDP reader, the hostname is not
used and must be omitted unless it is a valid UDP multicast
address.
+[libhdfs] namenode=str The host name or IP address of a HDFS cluster namenode to contact.
[netsplice] port=int
[net] port=int The TCP or UDP port to bind to or connect to. If this is used
with numjobs to spawn multiple instances of the same job type, then this will
be the starting port number since fio will use a range of ports.
+[libhdfs] port=int the listening port of the HFDS cluster namenode.
[netsplice] interface=str
[net] interface=str The IP address of the network interface used to send or
[mtd] skip_bad=bool Skip operations against known bad blocks.
+[libhdfs] hdfsdirectory libhdfs will create chunk in this HDFS directory
+[libhdfs] chunck_size the size of the chunck to use for each file.
+
6.0 Interpreting the output
---------------------------
projects / fio.git / blobdiff