.. option:: ioengine=str
- Defines how the job issues I/O to the file. The following types are defined:
+ fio supports 2 kinds of performance measurement: I/O and file/directory operation.
+
+ I/O engines define how the job issues I/O to the file. The following types are defined:
**sync**
Basic :manpage:`read(2)` or :manpage:`write(2)`
absolute or relative. See :file:`engines/skeleton_external.c` for
details of writing an external I/O engine.
- **filecreate**
- Simply create the files and do no I/O to them. You still need to
- set `filesize` so that all the accounting still occurs, but no
- actual I/O will be done other than creating the file.
-
- **filestat**
- Simply do stat() and do no I/O to the file. You need to set 'filesize'
- and 'nrfiles', so that files will be created.
- This engine is to measure file lookup and meta data access.
-
- **filedelete**
- Simply delete the files by unlink() and do no I/O to them. You need to set 'filesize'
- and 'nrfiles', so that the files will be created.
- This engine is to measure file delete.
-
- **dircreate**
- Simply create the directories and do no I/O to them. You still need to
- set `filesize` so that all the accounting still occurs, but no
- actual I/O will be done other than creating the directories.
-
- **dirstat**
- Simply do stat() and do no I/O to the directories. You need to set 'filesize'
- and 'nrfiles', so that directories will be created.
- This engine is to measure directory lookup and meta data access.
-
- **dirdelete**
- Simply delete the directories by rmdir() and do no I/O to them. You need to set 'filesize'
- and 'nrfiles', so that the directories will be created.
- This engine is to measure directory delete.
-
**libpmem**
Read and write using mmap I/O to a file on a filesystem
mounted with DAX on a persistent memory device through the PMDK
several instances to access the same device or file
simultaneously, but allow it for threads.
+ File/directory operation engines define how the job operates file or directory. The
+ following types are defined:
+
+ **filecreate**
+ Simply create the files and do no I/O to them. You still need to
+ set `filesize` so that all the accounting still occurs, but no
+ actual I/O will be done other than creating the file.
+ Example job file: filecreate-ioengine.fio.
+
+ **filestat**
+ Simply do stat() and do no I/O to the file. You need to set 'filesize'
+ and 'nrfiles', so that files will be created.
+ This engine is to measure file lookup and meta data access.
+ Example job file: filestat-ioengine.fio.
+
+ **filedelete**
+ Simply delete the files by unlink() and do no I/O to them. You need to set 'filesize'
+ and 'nrfiles', so that the files will be created.
+ This engine is to measure file delete.
+ Example job file: filedelete-ioengine.fio.
+
+ **dircreate**
+ Simply create the directories and do no I/O to them. You still need to
+ set `filesize` so that all the accounting still occurs, but no
+ actual I/O will be done other than creating the directories.
+ Example job file: dircreate-ioengine.fio.
+
+ **dirstat**
+ Simply do stat() and do no I/O to the directories. You need to set 'filesize'
+ and 'nrfiles', so that directories will be created.
+ This engine is to measure directory lookup and meta data access.
+ Example job file: dirstat-ioengine.fio.
+
+ **dirdelete**
+ Simply delete the directories by rmdir() and do no I/O to them. You need to set 'filesize'
+ and 'nrfiles', so that the directories will be created.
+ This engine is to measure directory delete.
+ Example job file: dirdelete-ioengine.fio.
+
+ For file and directory operation engines, there is no I/O throughput, then the
+ statistics data in report have different meanings. The meaningful output indexes are: 'iops' and 'clat'.
+ 'bw' is meaningless. Refer to section: "Interpreting the output" for more details.
+
+
I/O engine specific parameters
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
commit if available) functions were completed to when the I/O's
completion was reaped by fio.
+ For file and directory operation engines, **clat** denotes the time
+ to complete one file or directory operation.
+
+ **filecreate engine**:the time cost to create a new file
+
+ **filestat engine**: the time cost to look up an existing file
+
+ **filedelete engine**:the time cost to delete a file
+
+ **dircreate engine**: the time cost to create a new directory
+
+ **dirstat engine**: the time cost to look up an existing directory
+
+ **dirdelete engine**: the time cost to delete a directory
+
**lat**
Total latency. Same names as slat and clat, this denotes the time from
when fio created the I/O unit to completion of the I/O operation.
are on the same disk, since they are then competing for disk
access.
+ For file and directory operation engines, **bw** is meaningless.
+
**iops**
IOPS statistics based on measurements from discrete intervals.
For details see the description for bw above. See
:option:`iopsavgtime` to control the duration of the intervals.
Same values reported here as for bw except for percentage.
+ For file and directory operation engines, **iops** is the most
+ fundamental index to denote the performance.
+ It means how many files or directories can be operated per second.
+
+ **filecreate engine**:number of files can be created per second
+
+ **filestat engine**: number of files can be looked up per second
+
+ **filedelete engine**:number of files can be deleted per second
+
+ **dircreate engine**: number of directories can be created per second
+
+ **dirstat engine**: number of directories can be looked up per second
+
+ **dirdelete engine**: number of directories can be deleted per second
+
**lat (nsec/usec/msec)**
The distribution of I/O completion latencies. This is the time from when
I/O leaves fio and when it gets completed. Unlike the separate
projects / fio.git / blobdiff