X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=7cab05379f612034abdc173f03acb8d7850f902f;hp=24beeb8adbd5fa1363d7305c279b6c0d288275c8;hb=e48676baa53074b429460c71fb2c9e0ac7ac7d8c;hpb=9f9214f243701626a04b4a0f9aceec03b8b40e0f diff --git a/HOWTO b/HOWTO index 24beeb8a..7cab0537 100644 --- a/HOWTO +++ b/HOWTO @@ -176,6 +176,8 @@ siint SI integer. A whole number value, which may contain a postfix 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 seperate such values. 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 @@ -211,6 +213,10 @@ filename=str Fio normally makes up a filename based on the job name, a job to open /dev/sda and /dev/sdb as the two working files, you would use filename=/dev/sda:/dev/sdb +opendir=str Tell fio to recursively add any file it can find in this + directory and down the file system tree. + +readwrite=str rw=str Type of io pattern. Accepted values are: read Sequential reads @@ -222,11 +228,25 @@ rw=str Type of io pattern. Accepted values are: For the mixed io types, the default is to split them 50/50. For certain types of io the result may still be skewed a bit, - since the speed may be different. + since the speed may be different. It is possible to specify + a number of IO's to do before getting a new offset - this + is only useful for random IO, where fio would normally + generate a new random offset for every IO. If you append + eg 8 to randread, you would get a new random offset for + every 8 IO's. The result would be a seek for only every 8 + IO's, instead of for every IO. Use rw=randread:8 to specify + that. randrepeat=bool For random IO workloads, seed the generator in a predictable way so that results are repeatable across repetitions. +fadvise_hint=bool By default, fio will use fadvise() to advise the kernel + on what IO patterns it is likely to issue. Sometimes you + want to test specific IO patterns without telling the + kernel about it, in which case you can disable this option. + 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. This may describe the size of the single file the job uses, or it may be divided between the number of files in the job. If the @@ -234,6 +254,12 @@ size=siint The total size of file io for this job. This may describe size if larger than the current file size. If this parameter is not given and the file exists, the file size will be used. +filesize=siint 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. + +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 @@ -244,6 +270,7 @@ 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. +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 io unit will always be a multiple of the minimum value @@ -251,6 +278,7 @@ bsrange=irange Instead of giving a single block size, specify a range writes, however a second range can be given after a comma. See bs=. +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 direct IO, as that normally requires sector alignment. @@ -316,6 +344,14 @@ ioengine=str Defines how the job issues io to the file. The following will cause that job to do nothing but burn 85% of the CPU. + guasi The GUASI IO engine is the Generic Userspace + Asyncronous Syscall Interface approach + to async IO. See + + http://www.xmailserver.org/guasi-lib.html + + for more info on GUASI. + external Prefix to specify loading an external IO engine object file. Append the engine filename, eg ioengine=external:/tmp/foo.o @@ -358,6 +394,10 @@ overwrite=bool If writing to a file, setup the file first and do overwrites. end_fsync=bool If true, fsync file contents when the job exits. +fsync_on_close=bool If true, fio will fsync() a dirty file on close. + This differs from end_fsync in that it will happen on every + file close, not just at the end of the job. + rwmixcycle=int Value in milliseconds describing how often to switch between reads and writes for a mixed workload. The default is 500 msecs. @@ -404,7 +444,16 @@ thinktime_blocks rate=int Cap the bandwidth used by this job to this number of KiB/sec. ratemin=int Tell fio to do whatever it can to maintain at least this - bandwidth. + bandwidth. Failing to meet this requirement, will cause + the job to exit. + +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. + +rate_iops_min=int If fio doesn't meet this rate of IO, it will cause + the job to exit. ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number of milliseconds. @@ -429,6 +478,7 @@ invalidate=bool Invalidate the buffer/page cache parts for this file prior sync=bool Use sync io for buffered writes. For the majority of the io engines, this means using O_SYNC. +iomem=str mem=str Fio can use various types of memory as the io unit buffer. The allowed values are: @@ -505,13 +555,31 @@ verify=str If writing to a file, fio can verify the file contents crc32 Use a crc32 sum of the data area and store it in the header of each block. + null Only pretend to verify. Useful for testing + internals with ioengine=null, not for much + else. + This option can be used for repeated burn-in tests of a system to make sure that the written data is also correctly read back. +verifysort=bool If set, fio will sort written verify blocks when it deems + it faster to read them back in a sorted manner. This is + often the case when overwriting an existing file, since + the blocks are already laid out in the file system. You + can ignore this option unless doing huge amounts of really + fast IO where the red-black tree sorting CPU time becomes + significant. + stonewall Wait for preceeding jobs in the job file to exit, before starting this one. Can be used to insert serialization - points in the job file. + points in the job file. A stone wall also implies starting + a new reporting group. + +new_group Start a new reporting group. If this option isn't given, + jobs in a file will be part of the same reporting group + unless seperated by a stone wall (or if it's a group + by itself, with the numjobs option). numjobs=int Create the specified number of clones of this job. May be used to setup a larger number of threads/processes doing @@ -624,7 +692,7 @@ they denote: io= Number of megabytes io performed bw= Average bandwidth rate runt= The runtime of that thread - slat= Submission latency (avg being the average, dev being the + slat= Submission latency (avg being the average, stdev being the standard deviation). This is the time it took to submit the io. For sync io, the slat is really the completion latency, since queue/complete is one operation there.