X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=d3ead19782796af8dc5b0b496a65318cc3bcf210;hp=da7529fc93f2767ff8a13d3088feb425ca63052b;hb=14d0261ecd26020dfc114e1240c35e6dcca14cff;hpb=65fa28ca25ff0128b13d8ab6b3a0f9f75e33825f diff --git a/HOWTO b/HOWTO index da7529fc..d3ead197 100644 --- a/HOWTO +++ b/HOWTO @@ -198,7 +198,7 @@ sections. ------------------------- fio also supports environment variable expansion in job files. Any -substring of the form "${VARNAME}" as part of an option value (in other +sub-string of the form "${VARNAME}" as part of an option value (in other words, on the right of the `='), will be expanded to the value of the environment variable called VARNAME. If no such environment variable is defined, or VARNAME is the empty string, the empty string will be @@ -387,6 +387,8 @@ rw=str Type of io pattern. Accepted values are: randread Random reads rw,readwrite Sequential mixed reads and writes randrw Random mixed reads and writes + trimwrite Mixed trims and writes. Blocks will be + trimmed first, then written to. 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, @@ -433,6 +435,7 @@ unified_rw_reporting=bool Fio normally reports statistics on a per randrepeat=bool For random IO workloads, seed the generator in a predictable way so that results are repeatable across repetitions. + Defaults to true. randseed=int Seed the random number generators based on this seed value, to be able to control what sequence of output is being generated. @@ -620,7 +623,16 @@ buffer_pattern=str If set, fio will fill the io buffers with this the other options related to buffer contents. The setting can be any pattern of bytes, and can be prefixed with 0x for hex values. It may also be a string, where the string must then - be wrapped with "". + be wrapped with "", e.g.: + + buffer_pattern="abcd" + or + buffer_pattern=-12 + or + buffer_pattern=0xdeadface + + Also you can combine everything together in any order: + buffer_pattern=0xdeadface"abcd"-12 dedupe_percentage=int If set, fio will generate this percentage of identical buffers when writing. These buffers will be @@ -818,6 +830,18 @@ iodepth_low=int The low water mark indicating when to start filling after fio has filled the queue of 16 requests, it will let the depth drain down to 4 before starting to fill it again. +io_submit_mode=str This option controls how fio submits the IO to + the IO engine. The default is 'inline', which means that the + fio job threads submit and reap IO directly. If set to + 'offload', the job threads will offload IO submission to a + dedicated pool of IO threads. This requires some coordination + and thus has a bit of extra overhead, especially for lower + queue depth IO where it can increase latencies. The benefit + is that fio can manage submission rates independently of + the device completion rates. This avoids skewed latency + reporting if IO gets back up on the device side (the + coordinated omission problem). + direct=bool If value is true, use non-buffered io. This is usually O_DIRECT. Note that ZFS on Solaris doesn't support direct io. On Windows the synchronous ioengines don't support direct io. @@ -860,8 +884,8 @@ fsync=int If writing to a file, issue a sync of the dirty data fdatasync=int Like fsync= but uses fdatasync() to only sync data and not metadata blocks. - In FreeBSD and Windows there is no fdatasync(), this falls back to - using fsync() + In FreeBSD and Windows there is no fdatasync(), this falls back + to using fsync() sync_file_range=str:val Use sync_file_range() for every 'val' number of write operations. Fio will track range of writes that @@ -946,6 +970,8 @@ random_generator=str Fio supports the following engines for generating tausworthe Strong 2^88 cycle random number generator lfsr Linear feedback shift register generator + tausworthe64 Strong 64-bit 2^258 cycle random number + generator Tausworthe is a strong random number generator, but it requires tracking on the side if we want to ensure that @@ -1184,6 +1210,17 @@ create_only=bool If true, fio will only run the setup phase of the job. that will be done. The actual job contents are not executed. +allow_file_create=bool If true, fio is permitted to create files as part + of its workload. This is the default behavior. If this + option is false, then fio will error out if the files it + needs to use don't already exist. Default: true. + +allow_mounted_write=bool If this isn't set, fio will abort jobs that + are destructive (eg that write) to what appears to be a + mounted device or partition. This should help catch creating + inadvertently destructive tests, not realizing that the test + will destroy data on the mounted file system. Default: false. + 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 @@ -1211,7 +1248,12 @@ do_verify=bool Run the verify phase after a write phase. Only makes sense if verify is set. Defaults to 1. verify=str If writing to a file, fio can verify the file contents - after each iteration of the job. The allowed values are: + after each iteration of the job. Each verification method also implies + verification of special header, which is written to the beginning of + each block. This header also includes meta information, like offset + of the block, block number, timestamp when block was written, etc. + verify=str can be combined with verify_pattern=str option. + The allowed values are: md5 Use an md5 sum of the data area and store it in the header of each block. @@ -1247,11 +1289,17 @@ verify=str If writing to a file, fio can verify the file contents sha1 Use optimized sha1 as the checksum function. - meta Write extra information about each io - (timestamp, block number etc.). The block - number is verified. The io sequence number is - verified for workloads that write data. - See also verify_pattern. + meta This option is deprecated, since now meta information is + included in generic verification header and meta verification + happens by default. For detailed information see the description + of the verify=str setting. This option is kept because of + compatibility's sake with old configurations. Do not use it. + + pattern Verify a strict pattern. Normally fio includes + a header with some basic information and + checksumming, but if this option is set, only + the specific pattern set with 'verify_pattern' + is verified. null Only pretend to verify. Useful for testing internals with ioengine=null, not for much @@ -1290,7 +1338,14 @@ verify_pattern=str If set, fio will fill the io buffers with this buffer at the time(it can be either a decimal or a hex number). The verify_pattern if larger than a 32-bit quantity has to be a hex number that starts with either "0x" or "0X". Use - with verify=meta. + with verify=str. Also, verify_pattern supports %o format, + which means that for each block offset will be written and + then verifyied back, e.g.: + + verify_pattern=%o + + Or use combination of everything: + verify_pattern=0xff%o"abcd"-12 verify_fatal=bool Normally fio will keep checking the entire contents before quitting on a block verification failure. If this @@ -1419,6 +1474,16 @@ replay_redirect=str While replaying I/O patterns using read_iolog the independent fio invocations. Unfortuantely this also breaks the strict time ordering between multiple device accesses. +replay_align=int Force alignment of IO offsets and lengths in a trace + to this power of 2 value. + +replay_scale=int Scale sector offsets down by this factor when + replaying traces. + +per_job_logs=bool If set, this generates bw/clat/iops log with per + file private filenames. If not set, jobs with identical names + will share the log filename. Default: true. + 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 @@ -1426,7 +1491,8 @@ write_bw_log=str If given, write a bandwidth log of the jobs in this job graphs. See write_lat_log for behaviour of given filename. For this option, the suffix is _bw.x.log, where x is the index of the job (1..N, where N is the number of - jobs). + jobs). If 'per_job_logs' is false, then the filename will not + include the job index. write_lat_log=str Same as write_bw_log, except that this option stores io submission, completion, and total latencies instead. If no @@ -1439,13 +1505,17 @@ write_lat_log=str Same as write_bw_log, except that this option stores io The actual log names will be foo_slat.x.log, foo_clat.x.log, and foo_lat.x.log, where x is the index of the job (1..N, where N is the number of jobs). This helps fio_generate_plot - fine the logs automatically. + fine the logs automatically. If 'per_job_logs' is false, then + the filename will not include the job index. + write_iops_log=str Same as write_bw_log, but writes IOPS. If no filename is given with this option, the default filename of "jobname_type.x.log" is used,where x is the index of the job (1..N, where N is the number of jobs). Even if the filename - is given, fio will still append the type of log. + is given, fio will still append the type of log. If + 'per_job_logs' is false, then the filename will not include + the job index. log_avg_msec=int By default, fio will log an entry in the iops, latency, or bw log for every IO that completes. When writing to the @@ -1907,18 +1977,18 @@ Split up, the format is as follows: terse version, fio version, jobname, groupid, error READ status: Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec) - Submission latency: min, max, mean, deviation (usec) - Completion latency: min, max, mean, deviation (usec) + Submission latency: min, max, mean, stdev (usec) + Completion latency: min, max, mean, stdev (usec) Completion latency percentiles: 20 fields (see below) - Total latency: min, max, mean, deviation (usec) - Bw (KB/s): min, max, aggregate percentage of total, mean, deviation + Total latency: min, max, mean, stdev (usec) + Bw (KB/s): min, max, aggregate percentage of total, mean, stdev WRITE status: Total IO (KB), bandwidth (KB/sec), IOPS, runtime (msec) - Submission latency: min, max, mean, deviation (usec) - Completion latency: min, max, mean, deviation (usec) + Submission latency: min, max, mean, stdev (usec) + Completion latency: min, max, mean, stdev(usec) Completion latency percentiles: 20 fields (see below) - Total latency: min, max, mean, deviation (usec) - Bw (KB/s): min, max, aggregate percentage of total, mean, deviation + Total latency: min, max, mean, stdev (usec) + Bw (KB/s): min, max, aggregate percentage of total, mean, stdev CPU usage: user, system, context switches, major faults, minor faults IO depths: <=1, 2, 4, 8, 16, 32, >=64 IO latencies microseconds: <=2, 4, 10, 20, 50, 100, 250, 500, 750, 1000 @@ -1996,6 +2066,7 @@ before it can be used with this format. The offset and length are given in bytes. The action can be one of these: wait Wait for 'offset' microseconds. Everything below 100 is discarded. + The time is relative to the previous wait statement. read Read 'length' bytes beginning from 'offset' write Write 'length' bytes beginning from 'offset' sync fsync() the file