X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=40233bd90e5c1cf43a47541b8367506a46327dc5;hp=c99662c67255803fde30ceb0998e580715e83bbb;hb=8a68c41c2e7e0a1d5128e7e30ab673a6699c2f45;hpb=37db59d6ef74a8e6f5625c65dfbf4b72fd5fa84d diff --git a/HOWTO b/HOWTO index c99662c6..40233bd9 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 @@ -623,7 +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 @@ -803,8 +812,10 @@ 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 @@ -814,6 +825,31 @@ 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. @@ -1239,7 +1275,12 @@ 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. @@ -1275,11 +1316,11 @@ 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 @@ -1324,7 +1365,14 @@ 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