X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=482d69651c0362c3afd5863512dc32f7d73f3733;hp=cdb7b013591b00078a05f0ba04b34ca8a0c4d182;hb=a3f001f5f679ae4efc5f34f682b16a2673ec2bac;hpb=ca09be4b1a8e97f0bca5cfbddb399899cf561eaa diff --git a/HOWTO b/HOWTO index cdb7b013..482d6965 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. @@ -460,25 +463,32 @@ 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. +fadvise_stream=int Notify the kernel what write stream ID to place these + writes under. Only supported on Linux. Note, this option + may change going forward. + 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 nrfiles and filesize options are given, - fio will divide this size between the available files - specified by the job. If not set, fio will use the full - size of the given files or devices. If the files do not - exist, size must be given. It is also possible to give - size as a percentage between 1 and 100. If size=20% is - given, fio will use 20% of the full size of the given - files or devices. - + limited by other options (such as 'runtime', for instance, + or increased/decreased by 'io_size'). Unless specific nrfiles + and filesize options are given, fio will divide this size + between the available files specified by the job. If not set, + fio will use the full size of the given files or devices. + If the files do not exist, size must be given. It is also + possible to give size as a percentage between 1 and 100. If + size=20% is given, fio will use 20% of the full size of the + given files or devices. + +io_size=int io_limit=int Normally fio operates within the region set by 'size', which means that the 'size' option sets both the region and size of IO to be performed. Sometimes that is not what you want. With this option, it is possible to define just the amount of IO that fio should do. For instance, if 'size' is set to 20G and - 'io_limit' is set to 5G, fio will perform IO within the first - 20G but exit when 5G have been done. + 'io_size' is set to 5G, fio will perform IO within the first + 20G but exit when 5G have been done. The opposite is also + possible - if 'size' is set to 20G, and 'io_size' is set to + 40G, then fio will do 40G of IO within the 0..20G region. filesize=int Individual file sizes. May be a range, in which case fio will select sizes for files at random within the given range @@ -575,8 +585,6 @@ bs_is_seq_rand If this option is set, fio will use the normal read,write zero_buffers If this option is given, fio will init the IO buffers to all zeroes. The default is to fill them with random data. - The resulting IO buffers will not be completely zeroed, - unless scramble_buffers is also turned off. refill_buffers If this option is given, fio will refill the IO buffers on every submit. The default is to only fill it at init @@ -594,9 +602,12 @@ scramble_buffers=bool If refill_buffers is too costly and the target is buffer_compress_percentage=int If this is set, then fio will attempt to provide IO buffer content (on WRITEs) that compress to the specified level. Fio does this by providing a mix of - random data and zeroes. Note that this is per block size - unit, for file/disk wide compression level that matches - this setting, you'll also want to set refill_buffers. + random data and a fixed pattern. The fixed pattern is either + zeroes, or the pattern specified by buffer_pattern. If the + pattern option is used, it might skew the compression ratio + slightly. Note that this is per block size unit, for file/disk + wide compression level that matches this setting, you'll also + want to set refill_buffers. buffer_compress_chunk=int See buffer_compress_percentage. This setting allows fio to manage how big the ranges of random @@ -612,7 +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 @@ -747,20 +767,23 @@ ioengine=str Defines how the job issues io to the file. The following defines engine specific options. libhdfs Read and write through Hadoop (HDFS). - The 'filename' option is used to specify host, - port of the hdfs name-node to connect. This - engine interprets offsets a little + This engine interprets offsets a little differently. In HDFS, files once created cannot be modified. So random writes are not possible. To imitate this, libhdfs engine - expects bunch of small files to be created - over HDFS, and engine will randomly pick a - file out of those files based on the offset - generated by fio backend. (see the example - job file to create such files, use rw=write - option). Please note, you might want to set - necessary environment variables to work with - hdfs/libhdfs properly. + creates bunch of small files, and engine will + pick a file out of those files based on the + offset enerated by fio backend. Each jobs uses + it's own connection to HDFS. + + mtd Read, write and erase an MTD character device + (e.g., /dev/mtd0). Discards are treated as + erases. Depending on the underlying device + type, the I/O may have to go in a certain + pattern, e.g., on NAND, writing sequentially + to erase blocks and discarding before + overwriting. The writetrim mode works well + for this constraint. external Prefix to specify loading an external IO engine object file. Append the engine @@ -783,8 +806,10 @@ iodepth_batch_submit=int iodepth_batch=int This defines how many pieces of IO to submit at once. It defaults to 1 which means that we submit each IO as soon as it is available, but can be raised to submit - bigger batches of IO at the time. + bigger batches of IO at the time. If it is set to 0 the iodepth + value will be used. +iodepth_batch_complete_min=int iodepth_batch_complete=int This defines how many pieces of IO to retrieve at once. It defaults to 1 which means that we'll ask for a minimum of 1 IO in the retrieval process from @@ -794,6 +819,31 @@ iodepth_batch_complete=int This defines how many pieces of IO to retrieve events before queuing more IO. This helps reduce IO latency, at the cost of more retrieval system calls. +iodepth_batch_complete_max=int This defines maximum pieces of IO to + retrieve at once. This variable should be used along with + iodepth_batch_complete_min=int variable, specifying the range + of min and max amount of IO which should be retrieved. By default + it is equal to iodepth_batch_complete_min value. + + Example #1: + + iodepth_batch_complete_min=1 + iodepth_batch_complete_max= + + which means that we will retrieve at leat 1 IO and up to the + whole submitted queue depth. If none of IO has been completed + yet, we will wait. + + Example #2: + + iodepth_batch_complete_min=0 + iodepth_batch_complete_max= + + which means that we can retrieve up to the whole submitted + queue depth, but if none of IO has been completed yet, we will + NOT wait and immediately exit the system call. In this example + we simply do polling. + iodepth_low=int The low water mark indicating when to start filling the queue again. Defaults to the same as iodepth, meaning that fio will attempt to keep the queue full at all times. @@ -801,6 +851,18 @@ 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. @@ -843,8 +905,8 @@ 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 @@ -913,10 +975,10 @@ norandommap Normally fio will cover every block of the file when doing random IO. If this option is given, fio will just get a 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= if and only if multiple - blocksizes (via bsrange=) are used, since fio only tracks - complete rewrites of blocks. + some blocks may be read/written more than once. If this option + is used with verify= and multiple blocksizes (via bsrange=), + only intact blocks are verified, i.e., partially-overwritten + blocks are ignored. softrandommap=bool See norandommap. If fio runs with the random block map enabled and it fails to allocate the map, if this option is @@ -929,6 +991,8 @@ 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 @@ -979,7 +1043,7 @@ rate=int Cap the bandwidth used by this job. The number is in bytes/sec, 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 +rate_min=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 same format as rate is used for read vs write separation. @@ -994,6 +1058,15 @@ rate_iops_min=int If fio doesn't meet this rate of IO, it will cause the job to exit. The same format as rate is used for read vs write separation. +rate_process=str This option controls how fio manages rated IO + submissions. The default is 'linear', which submits IO in a + linear fashion with fixed delays between IOs that gets + adjusted based on IO completion rates. If this is set to + 'poisson', fio will submit IO based on a more real world + random request flow, known as the Poisson process + (https://en.wikipedia.org/wiki/Poisson_process). The lambda + will be 10^6 / IOPS for the given workload. + latency_target=int If set, fio will attempt to find the max performance point that the given workload will run at while maintaining a latency below this target. The values is given in microseconds. @@ -1011,7 +1084,7 @@ latency_percentile=float The percentage of IOs that must fall within the max_latency=int If set, fio will exit the job if it exceeds this maximum latency. It will exit with an ETIME error. -ratecycle=int Average bandwidth for 'rate' and 'ratemin' over this number +rate_cycle=int Average bandwidth for 'rate' and 'rate_min' over this number of milliseconds. cpumask=int Set the CPU affinity of this job. The parameter given is a @@ -1107,6 +1180,9 @@ mem=str Fio can use various types of memory as the io unit buffer. backing. Append filename after mmaphuge, ala mem=mmaphuge:/hugetlbfs/file + mmapshared Same as mmap, but use a MMAP_SHARED + mapping. + The area allocated is a function of the maximum allowed bs size for the job, multiplied by the io depth given. Note that for shmhuge and mmaphuge to work, the system must have @@ -1145,6 +1221,9 @@ exitall When one job finishes, terminate the rest. The default is to wait for each job to finish, sometimes that is not the desired action. +exitall_on_error When one job finishes in error, terminate the rest. The + default is to wait for each job to finish. + bwavgtime=int Average the calculated bandwidth over the given time. Value is specified in milliseconds. @@ -1167,6 +1246,17 @@ 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 @@ -1194,7 +1284,12 @@ 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. @@ -1230,11 +1325,17 @@ 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 @@ -1273,7 +1374,14 @@ 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 @@ -1402,6 +1510,16 @@ 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 @@ -1409,7 +1527,8 @@ 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 @@ -1422,13 +1541,17 @@ 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 @@ -1454,11 +1577,20 @@ log_compression=int If this is set, fio will compress the IO logs as in the specified log file. This feature depends on the availability of zlib. -log_store_compressed=bool If set, and log_compression is also set, - fio will store the log files in a compressed format. They - can be decompressed with fio, using the --inflate-log - command line parameter. The files will be stored with a - .fz suffix. +log_compression_cpus=str Define the set of CPUs that are allowed to + handle online log compression for the IO jobs. This can + provide better isolation between performance sensitive jobs, + and background compression work. + +log_store_compressed=bool If set, fio will store the log files in a + compressed format. They can be decompressed with fio, using + the --inflate-log command line parameter. The files will be + stored with a .fz suffix. + +block_error_percentiles=bool If set, record errors in trim block-sized + units from writes and trims and output a histogram of + how many trims it took to get to errors, and what kind + of error was encountered. lockmem=int Pin down the specified amount of memory with mlock(2). Can potentially be used instead of removing memory or booting @@ -1499,13 +1631,13 @@ clat_percentiles=bool Enable the reporting of percentiles of completion latencies. percentile_list=float_list Overwrite the default list of percentiles - for completion latencies. Each number is a floating - number in the range (0,100], and the maximum length of - the list is 20. Use ':' to separate the numbers, and - list the numbers in ascending order. For example, - --percentile_list=99.5:99.9 will cause fio to report - the values of completion latency below which 99.5% and - 99.9% of the observed latencies fell, respectively. + for completion latencies and the block error histogram. + Each number is a floating number in the range (0,100], + and the maximum length of the list is 20. Use ':' + to separate the numbers, and list the numbers in ascending + order. For example, --percentile_list=99.5:99.9 will cause + fio to report the values of completion latency below which + 99.5% and 99.9% of the observed latencies fell, respectively. clocksource=str Use the given clocksource as the base of timing. The supported options are: @@ -1647,11 +1779,13 @@ that defines them is selected. If the job is a TCP listener or UDP reader, the hostname is not used and must be omitted unless it is a valid UDP multicast address. +[libhdfs] namenode=str The host name or IP address of a HDFS cluster namenode to contact. [netsplice] port=int [net] port=int The TCP or UDP port to bind to or connect to. If this is used with numjobs to spawn multiple instances of the same job type, then this will be the starting port number since fio will use a range of ports. +[libhdfs] port=int the listening port of the HFDS cluster namenode. [netsplice] interface=str [net] interface=str The IP address of the network interface used to send or @@ -1708,6 +1842,10 @@ be the starting port number since fio will use a range of ports. 1 : allocate space immidietly inside defragment event, and free right after event +[mtd] skip_bad=bool Skip operations against known bad blocks. + +[libhdfs] hdfsdirectory libhdfs will create chunk in this HDFS directory +[libhdfs] chunck_size the size of the chunck to use for each file. 6.0 Interpreting the output @@ -1884,18 +2022,18 @@ 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 @@ -1973,6 +2111,7 @@ 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 @@ -1993,3 +2132,81 @@ An unit work is defined as touching a full page of unsigned characters. Mean and standard deviation of time to complete an unit work is reported in "unit work" section. Options can be chosen to report detailed percpu idleness or overall system idleness by aggregating percpu stats. + + +10.0 Verification and triggers +------------------------------ +Fio is usually run in one of two ways, when data verification is done. The +first is a normal write job of some sort with verify enabled. When the +write phase has completed, fio switches to reads and verifies everything +it wrote. The second model is running just the write phase, and then later +on running the same job (but with reads instead of writes) to repeat the +same IO patterns and verify the contents. Both of these methods depend +on the write phase being completed, as fio otherwise has no idea how much +data was written. + +With verification triggers, fio supports dumping the current write state +to local files. Then a subsequent read verify workload can load this state +and know exactly where to stop. This is useful for testing cases where +power is cut to a server in a managed fashion, for instance. + +A verification trigger consists of two things: + +1) Storing the write state of each job +2) Executing a trigger command + +The write state is relatively small, on the order of hundreds of bytes +to single kilobytes. It contains information on the number of completions +done, the last X completions, etc. + +A trigger is invoked either through creation ('touch') of a specified +file in the system, or through a timeout setting. If fio is run with +--trigger-file=/tmp/trigger-file, then it will continually check for +the existence of /tmp/trigger-file. When it sees this file, it will +fire off the trigger (thus saving state, and executing the trigger +command). + +For client/server runs, there's both a local and remote trigger. If +fio is running as a server backend, it will send the job states back +to the client for safe storage, then execute the remote trigger, if +specified. If a local trigger is specified, the server will still send +back the write state, but the client will then execute the trigger. + +10.1 Verification trigger example +--------------------------------- +Lets say we want to run a powercut test on the remote machine 'server'. +Our write workload is in write-test.fio. We want to cut power to 'server' +at some point during the run, and we'll run this test from the safety +or our local machine, 'localbox'. On the server, we'll start the fio +backend normally: + +server# fio --server + +and on the client, we'll fire off the workload: + +localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger-remote="bash -c \"echo b > /proc/sysrq-triger\"" + +We set /tmp/my-trigger as the trigger file, and we tell fio to execute + +echo b > /proc/sysrq-trigger + +on the server once it has received the trigger and sent us the write +state. This will work, but it's not _really_ cutting power to the server, +it's merely abruptly rebooting it. If we have a remote way of cutting +power to the server through IPMI or similar, we could do that through +a local trigger command instead. Lets assume we have a script that does +IPMI reboot of a given hostname, ipmi-reboot. On localbox, we could +then have run fio with a local trigger instead: + +localbox$ fio --client=server --trigger-file=/tmp/my-trigger --trigger="ipmi-reboot server" + +For this case, fio would wait for the server to send us the write state, +then execute 'ipmi-reboot server' when that happened. + +10.1 Loading verify state +------------------------- +To load store write state, read verification job file must contain +the verify_state_load option. If that is set, fio will load the previously +stored state. For a local fio run this is done by loading the files directly, +and on a client/server run, the server backend will ask the client to send +the files over and load them from there.