X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=55662d34bae7d7cc2ed46a6b87d2a5fa971568ee;hp=f4f596a4c02e7880a0394f809a1f24aae05a6737;hb=e8462bd8250cf3ff2d41f17e1a4d4cefc70b6b37;hpb=fc6bd43c62196441607e6c36ec66bd0e16f9e4ef diff --git a/HOWTO b/HOWTO index f4f596a4..55662d34 100644 --- a/HOWTO +++ b/HOWTO @@ -230,7 +230,7 @@ description=str Text description of the job. Doesn't do anything except dump this text description when this job is run. It's not parsed. -directory=str Prefix filenames with this directory. Used to places files +directory=str Prefix filenames with this directory. Used to place files in a different location than "./". filename=str Fio normally makes up a filename based on the job name, @@ -250,7 +250,7 @@ filename=str Fio normally makes up a filename based on the job name, opendir=str Tell fio to recursively add any file it can find in this directory and down the file system tree. -lockfile=str Fio defaults to not doing any locking files before it does +lockfile=str Fio defaults to not locking any files before it does IO to them. If a file or file descriptor is shared, fio can serialize IO to that file to make the end result consistent. This is usual for emulating real workloads that @@ -303,7 +303,7 @@ fadvise_hint=bool By default, fio will use fadvise() to advise the kernel size=int The total size of file io for this job. Fio will run until this many bytes has been transferred, unless runtime is limited by other options (such as 'runtime', for instance). - Unless specific nr_files and filesize options are given, + Unless specific nrfiles and filesize options are given, fio will divide this size between the available files specified by the job. @@ -314,7 +314,8 @@ filesize=int Individual file sizes. May be a range, in which case fio 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 @@ -529,6 +530,9 @@ fsync=int If writing to a file, issue a sync of the dirty data 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 @@ -546,7 +550,9 @@ rwmixread=int How large a percentage of the mix should be reads. 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 @@ -588,19 +594,29 @@ thinktime_blocks defaults to 1 which will make fio wait 'thinktime' usecs after every block. -rate=int Cap the bandwidth used by this job to this number of KiB/sec. +rate=int Cap the bandwidth used by this job. The number is in bytes/sec, + the normal postfix rules apply. You can use rate=500k to limit + reads and writes to 500k each, or you can specify read and + writes separately. Using rate=1m,500k would limit reads to + 1MB/sec and writes to 500KB/sec. Capping only reads or + writes can be done with rate=,500k or rate=500k,. The former + 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 bandwidth. Failing to meet this requirement, will cause - the job to exit. + the job to exit. The same format as rate is used for + read vs write separation. rate_iops=int Cap the bandwidth to this number of IOPS. Basically the same as rate, just specified independently of bandwidth. If the job is given a block size range instead of a fixed value, - the smallest block size is used as the metric. + the smallest block size is used as the metric. The same format + as rate is used for read vs write seperation. rate_iops_min=int If fio doesn't meet this rate of IO, it will cause - the job to exit. + the job to exit. The same format as rate is used for read vs + write seperation. ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number of milliseconds. @@ -688,6 +704,15 @@ mem=str Fio can use various types of memory as the io unit buffer. 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. @@ -713,6 +738,14 @@ create_fsync=bool fsync the data file after creation. This is the create_on_open=bool Don't pre-setup the files for IO, just create open() when it's time to do IO to that file. +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. 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 set again and again. @@ -794,6 +827,16 @@ verify_fatal=bool Normally fio will keep checking the entire contents 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 @@ -874,7 +917,7 @@ 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 milliseconds. + cycles of the given time. In microseconds. disk_util=bool Generate disk utilization statistics, if the platform supports it. Defaults to on. @@ -910,6 +953,14 @@ gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of 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 @@ -928,6 +979,7 @@ Idle Run P Thread setup, but not started. C Thread created. I Thread initialized, waiting. + p Thread running pre-reading file(s). R Running, doing sequential reads. r Running, doing random reads. W Running, doing sequential writes.