fill_device=bool Sets size to something really large and waits for ENOSPC (no
space left on device) as the terminating condition. Only makes
- sense with sequential write.
+ sense with sequential write. For a read workload, the mount
+ point will be filled first then IO started on the result.
blocksize=int
bs=int The block size used for the io units. Defaults to 4k. Values
not sync the file. The exception is the sg io engine, which
synchronizes the disk cache anyway.
+fsyncdata=int Like fsync= but uses fdatasync() to only sync data and not
+ metadata blocks.
+
overwrite=bool If true, writes to a file will always overwrite existing
data. If the file doesn't already exist, it will be
created before the write phase begins. If the file exists
rwmixwrite=int How large a percentage of the mix should be writes. If both
rwmixread and rwmixwrite is given and the values do not add
up to 100%, the latter of the two will be used to override
- the first.
+ the first. This may interfere with a given rate setting,
+ if fio is asked to limit reads or writes to a certain rate.
+ If that is the case, then the distribution may be skewed.
norandommap Normally fio will cover every block of the file when doing
random IO. If this option is given, fio will just get a
location should point there. So if it's mounted in /huge,
you would use mem=mmaphuge:/huge/somefile.
+iomem_align=int This indiciates the memory alignment of the IO memory buffers.
+ Note that the given alignment is applied to the first IO unit
+ buffer, if using iodepth the alignment of the following buffers
+ are given by the bs used. In other words, if using a bs that is
+ a multiple of the page sized in the system, all buffers will
+ be aligned to this value. If using a bs that is not page
+ aligned, the alignment of subsequent IO memory buffers is the
+ sum of the iomem_align and bs used.
+
hugepage-size=int
Defines the size of a huge page. Must at least be equal
to the system setting, see /proc/meminfo. Defaults to 4MiB.
pre_read=bool If this is given, files will be pre-read into memory before
starting the given IO operation. This will also clear
the 'invalidate' flag, since it is pointless to pre-read
- and then drop the cache.
+ and then drop the cache. This will only work for IO engines
+ that are seekable, since they allow you to read the same data
+ multiple times. Thus it will not work on eg network or splice
+ IO.
unlink=bool Unlink the job files when done. Not the default, as repeated
runs of that job would then waste time recreating the file
before quitting on a block verification failure. If this
option is set, fio will exit the job on the first observed
failure.
+
+verify_async=int Fio will normally verify IO inline from the submitting
+ thread. This option takes an integer describing how many
+ async offload threads to create for IO verification instead,
+ causing fio to offload the duty of verifying IO contents
+ to one or more separate threads.
+
+verify_async_cpus=str Tell fio to set the given CPU affinity on the
+ async IO verification threads. See cpus_allowed for the
+ format used.
stonewall Wait for preceeding jobs in the job file to exit, before
starting this one. Can be used to insert serialization
for doing these time calls will be excluded from other
uses. Fio will manually clear it from the CPU mask of other
jobs.
+continue_on_error=bool Normally fio will exit the job on the first observed
+ failure. If this option is set, fio will continue the job when
+ there is a 'non-fatal error' (EIO or EILSEQ) until the runtime
+ is exceeded or the I/O size specified is completed. If this
+ option is used, there are two more stats that are appended,
+ the total error count and the first error. The error field
+ given in the stats is the first error that was hit during the
+ run.
6.0 Interpreting the output
projects / fio.git / blobdiff