X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=1390f386adca52a4c4ccdec3d60c6c730b9392e5;hp=f4efd281bbc72e2a4a54dfc233aab2310fa0643d;hb=afad68f778a764cbe57d4a5d54cbea32444aaa45;hpb=993bf48b48f2d9724afa3698a15070e77bc5d1c0 diff --git a/HOWTO b/HOWTO index f4efd281..1390f386 100644 --- a/HOWTO +++ b/HOWTO @@ -197,25 +197,25 @@ Some parameters take an option of a given type, such as an integer or a string. The following types are used: str String. This is a sequence of alpha characters. -int Integer. A whole number value, can be negative. If prefixed with - 0x, the integer is assumed to be of base 16 (hexadecimal). time Integer with possible time postfix. In seconds unless otherwise specified, use eg 10m for 10 minutes. Accepts s/m/h for seconds, minutes, and hours. -siint SI integer. A whole number value, which may contain a postfix +int SI integer. A whole number value, which may contain a postfix describing the base of the number. Accepted postfixes are k/m/g, meaning kilo, mega, and giga. So if you want to specify 4096, you could either write out '4096' or just give 4k. The postfixes signify base 2 values, so 1024 is 1k and 1024k is 1m and so on. If the option accepts an upper and lower range, use a colon ':' - or minus '-' to separate such values. See irange. + or minus '-' to separate such values. May also include a prefix + to indicate numbers base. If 0x is used, the number is assumed to + be hexadecimal. See irange. bool Boolean. Usually parsed as an integer, however only defined for true and false (1 and 0). irange Integer range with postfix. Allows value range to be given, such as 1024-4096. A colon may also be used as the separator, eg 1k:4k. If the option allows two sets of ranges, they can be specified with a ',' or '/' delimiter: 1k-4k/8k-32k. Also see - siint. + int. With the above in mind, here follows the complete list of fio job parameters. @@ -230,26 +230,27 @@ 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, thread number, and file number. If you want to share files between threads in a job or several jobs, specify a filename for each of them to override the default. If - the ioengine used is 'net', the filename is the host and - port to connect to in the format of =host/port. If the - ioengine is file based, you 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. '-' is a reserved - name, meaning stdin or stdout. Which of the two depends - on the read/write direction set. + the ioengine used is 'net', the filename is the host, port, + and protocol to use in the format of =host/port/protocol. + See ioengine=net for more. If the ioengine is file based, you + 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. '-' 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. -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 @@ -299,14 +300,14 @@ fadvise_hint=bool By default, fio will use fadvise() to advise the kernel If set, fio will use POSIX_FADV_SEQUENTIAL for sequential IO and POSIX_FADV_RANDOM for random IO. -size=siint The total size of file io for this job. Fio will run until +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. -filesize=siint Individual file sizes. May be a range, in which case fio +filesize=int Individual file sizes. May be a range, in which case fio will select sizes for files at random within the given range and limited to 'size' in total (if that is given). If not given, each created file is the same size. @@ -315,10 +316,10 @@ 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. -blocksize=siint -bs=siint The block size used for the io units. Defaults to 4k. Values - can be given for both read and writes. If a single siint is - given, it will apply to both. If a second siint is specified +blocksize=int +bs=int The block size used for the io units. Defaults to 4k. Values + can be given for both read and writes. If a single int is + given, it will apply to both. If a second int is specified after a comma, it will apply to writes only. In other words, the format is either bs=read_and_write or bs=read,write. bs=4k,8k will thus use 4k blocks for reads, and 8k blocks @@ -326,6 +327,14 @@ bs=siint The block size used for the io units. Defaults to 4k. Values can do so by passing an empty read size - bs=,8k will set 8k for writes and leave the read default value. +blockalign=int +ba=int At what boundary to align random IO offsets. Defaults to + the same as 'blocksize' the minimum blocksize given. + Minimum alignment is typically 512b for using direct IO, + though it usually depends on the hardware block size. This + option is mutually exclusive with using a random map for + files, so it will turn off that option. + blocksize_range=irange bsrange=irange Instead of giving a single block size, specify a range and fio will mix the issued io block sizes. The issued @@ -358,6 +367,15 @@ bssplit=str Sometimes you want even finer grained control of the always add up to 100, if bssplit is given a range that adds up to more, it will error out. + bssplit also supports giving separate splits to reads and + writes. The format is identical to what bs= accepts. You + have to separate the read and write parts with a comma. So + if you want a workload that has 50% 2k reads and 50% 4k reads, + while having 90% 4k writes and 10% 8k writes, you would + specify: + + bssplit=2k/50:4k/50,4k/90,8k/10 + blocksize_unaligned bs_unaligned If this option is given, any byte size value within bsrange may be used as a block range. This typically wont work with @@ -386,6 +404,10 @@ file_service_type=str Defines how fio decides which file from a job to roundrobin Round robin over open files. This is the default. + sequential Finish one file before moving on to + the next. Multiple files can still be + open depending on 'openfiles'. + The string can have a number appended, indicating how often to switch to a new file. So if option random:4 is given, fio will switch to a new random file after 4 ios @@ -401,7 +423,9 @@ ioengine=str Defines how the job issues io to the file. The following vsync Basic readv(2) or writev(2) IO. - libaio Linux native asynchronous io. + libaio Linux native asynchronous io. Note that Linux + may only support queued behaviour with + non-buffered IO (set direct=1 or buffered=0). posixaio glibc posix asynchronous io. @@ -429,9 +453,12 @@ ioengine=str Defines how the job issues io to the file. The following net Transfer over the network to given host:port. 'filename' must be set appropriately to - filename=host/port regardless of send + filename=host/port/protocol regardless of send or receive, if the latter only the port - argument is used. + argument is used. 'host' may be an IP address + or hostname, port is the port number to be used, + and protocol may be 'udp' or 'tcp'. If no + protocol is given, TCP is used. netsplice Like net, but uses splice/vmsplice to map data and send/receive. @@ -491,7 +518,7 @@ direct=bool If value is true, use non-buffered io. This is usually buffered=bool If value is true, use buffered io. This is the opposite of the 'direct' option. Defaults to true. -offset=siint Start io at the given offset in the file. The data before +offset=int Start io at the given offset in the file. The data before the given offset will not be touched. This effectively caps the file size at real_size - offset. @@ -526,9 +553,9 @@ norandommap Normally fio will cover every block of the file when doing new random offset without looking at past io history. This means that some blocks may not be read or written, and that some blocks may be read/written more than once. This option - is mutually exclusive with verify= for that reason, since - fio doesn't track potential block rewrites which may alter - the calculated checksum for that block. + is mutually exclusive with verify= if and only if multiple + blocksizes (via bsrange=) are used, since fio only tracks + complete rewrites of blocks. softrandommap See norandommap. If fio runs with the random block map enabled and it fails to allocate the map, if this option is set it @@ -583,11 +610,16 @@ cpumask=int Set the CPU affinity of this job. The parameter given is a the allowed CPUs to be 1 and 5, you would pass the decimal value of (1 << 1 | 1 << 5), or 34. See man sched_setaffinity(2). This may not work on all supported - operating systems or kernel versions. + operating systems or kernel versions. This option doesn't + work well for a higher CPU count than what you can store in + an integer mask, so it can only control cpus 1-32. For + boxes with larger CPU counts, use cpus_allowed. cpus_allowed=str Controls the same options as cpumask, but it allows a text setting of the permitted CPUs instead. So to use CPUs 1 and - 5, you would specify cpus_allowed=1,5. + 5, you would specify cpus_allowed=1,5. This options also + allows a range of CPUs. Say you wanted a binding to CPUs + 1, 5, and 8-15, you would set cpus_allowed=1,5,8-15. startdelay=time Start this job the specified number of seconds after fio has started. Only useful if the job file contains several @@ -656,7 +688,7 @@ 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. -hugepage-size=siint +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. Should probably always be a multiple of megabytes, so using @@ -678,6 +710,12 @@ create_serialize=bool If true, serialize the file creating for the jobs. create_fsync=bool fsync the data file after creation. This is the default. +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. + 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. @@ -738,11 +776,11 @@ verifysort=bool If set, fio will sort written verify blocks when it deems fast IO where the red-black tree sorting CPU time becomes significant. -verify_offset=siint Swap the verification header with data somewhere else +verify_offset=int Swap the verification header with data somewhere else in the block before writing. Its swapped back before verifying. -verify_interval=siint Write the verification header at a finer granularity +verify_interval=int Write the verification header at a finer granularity than the blocksize. It will be written for chunks the size of header_interval. blocksize should divide this evenly. @@ -786,9 +824,9 @@ thread fio defaults to forking jobs, however if this option is given, fio will use pthread_create(3) to create threads instead. -zonesize=siint Divide a file into zones of the specified size. See zoneskip. +zonesize=int Divide a file into zones of the specified size. See zoneskip. -zoneskip=siint Skip the specified number of bytes when zonesize data has +zoneskip=int Skip the specified number of bytes when zonesize data has been read. The two zone options can be used to only do io on zones of a file. @@ -804,16 +842,25 @@ read_iolog=str Open an iolog with the specified file name and replay the the file needs to be turned into a blkparse binary data file first (blktrace -d file_for_fio.bin). -write_bw_log If given, write a bandwidth log of the jobs in this job +write_bw_log=str If given, write a bandwidth log of the jobs in this job file. Can be used to store data of the bandwidth of the jobs in their lifetime. The included fio_generate_plots script uses gnuplot to turn these text files into nice - graphs. + graphs. See write_log_log for behaviour of given + filename. For this option, the postfix is _bw.log. + +write_lat_log=str Same as write_bw_log, except that this option stores io + completion latencies instead. If no filename is given + with this option, the default filename of "jobname_type.log" + is used. Even if the filename is given, fio will still + append the type of log. So if one specifies -write_lat_log Same as write_bw_log, except that this option stores io - completion latencies instead. + write_lat_log=foo -lockmem=siint Pin down the specified amount of memory with mlock(2). Can + The actual log names will be foo_clat.log and foo_slat.log. + This helps fio_generate_plot fine the logs automatically. + +lockmem=int Pin down the specified amount of memory with mlock(2). Can potentially be used instead of removing memory or booting with less memory to simulate a smaller amount of memory. @@ -830,7 +877,7 @@ 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. @@ -855,6 +902,18 @@ gtod_reduce=bool Enable all of the gettimeofday() reducing options we only do about 0.4% of the gtod() calls we would have done if all time keeping was enabled. +gtod_cpu=int Sometimes it's cheaper to dedicate a single thread of + execution to just getting the current time. Fio (and + databases, for instance) are very intensive on gettimeofday() + calls. With this option, you can set one CPU aside for + doing nothing but logging current time to a shared memory + location. Then the other threads/processes that run IO + workloads need only copy that segment, instead of entering + the kernel with a gettimeofday() call. The CPU set aside + for doing these time calls will be excluded from other + uses. Fio will manually clear it from the CPU mask of other + jobs. + 6.0 Interpreting the output --------------------------- @@ -879,7 +938,7 @@ I Thread initialized, waiting. M Running, doing mixed sequential reads/writes. m Running, doing mixed random reads/writes. F Running, currently waiting for fsync() -V Running, doing verification of written data. + V Running, doing verification of written data. E Thread exited, not reaped by main thread yet. _ Thread reaped.