X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=fio.1;h=4386f8577b8c6f8a63eb12b40d65b22d9b77d2c1;hp=92648558caca2b87b1cb26ccd74c248ce01d9df7;hb=2ce58465415fc4d900c4dd89b86acbcaa51d9dfb;hpb=c7d32225c3efe61c79470bc31bb369b33d3e3a88 diff --git a/fio.1 b/fio.1 index 92648558..4386f857 100644 --- a/fio.1 +++ b/fio.1 @@ -68,12 +68,11 @@ available ioengines. Convert \fIjobfile\fR to a set of command\-line options. .TP .BI \-\-readonly -Turn on safety read\-only checks, preventing writes. The \fB\-\-readonly\fR +Turn on safety read\-only checks, preventing writes and trims. The \fB\-\-readonly\fR option is an extra safety guard to prevent users from accidentally starting -a write workload when that is not desired. Fio will only write if -`rw=write/randwrite/rw/randrw' is given. This extra safety net can be used -as an extra precaution as \fB\-\-readonly\fR will also enable a write check in -the I/O engine core to prevent writes due to unknown user space bug(s). +a write or trim workload when that is not desired. Fio will only modify the +device under test if `rw=write/randwrite/rw/randrw/trim/randtrim/trimwrite' +is given. This safety net can be used as an extra precaution. .TP .BI \-\-eta \fR=\fPwhen Specifies when real\-time ETA estimate should be printed. \fIwhen\fR may @@ -758,7 +757,7 @@ Sequential reads. Sequential writes. .TP .B trim -Sequential trims (Linux block devices only). +Sequential trims (Linux block devices and SCSI character devices only). .TP .B randread Random reads. @@ -767,7 +766,7 @@ Random reads. Random writes. .TP .B randtrim -Random trims (Linux block devices only). +Random trims (Linux block devices and SCSI character devices only). .TP .B rw,readwrite Sequential mixed reads and writes. @@ -1121,7 +1120,9 @@ at past I/O history. This means that some blocks may not be read or written, and that some blocks may be read/written more than once. If this option is used with \fBverify\fR and multiple blocksizes (via \fBbsrange\fR), only intact blocks are verified, i.e., partially\-overwritten blocks are -ignored. +ignored. With an async I/O engine and an I/O depth > 1, it is possible for +the same block to be overwritten, which can cause verification errors. Either +do not use norandommap in this case, or also use the lfsr random generator. .TP .BI softrandommap \fR=\fPbool See \fBnorandommap\fR. If fio runs with the random block map enabled and @@ -1227,7 +1228,7 @@ 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: .RS .P -bssplit=2k/50:4k/50,4k/90,8k/10 +bssplit=2k/50:4k/50,4k/90:8k/10 .RE .P Fio supports defining up to 64 different weights for each data direction. @@ -1523,7 +1524,8 @@ SCSI generic sg v3 I/O. May either be synchronous using the SG_IO ioctl, or if the target is an sg character device we use \fBread\fR\|(2) and \fBwrite\fR\|(2) for asynchronous I/O. Requires \fBfilename\fR option to specify either block or -character devices. The sg engine includes engine specific options. +character devices. This engine supports trim operations. The +sg engine includes engine specific options. .TP .B null Doesn't transfer any data, just pretends to. This is mainly used to @@ -1828,6 +1830,33 @@ unit access (fua) flag. Default: 0. .BI (sg)writefua \fR=\fPbool With writefua option set to 1, write operations include the force unit access (fua) flag. Default: 0. +.TP +.BI (sg)sg_write_mode \fR=\fPstr +Specify the type of write commands to issue. This option can take three +values: +.RS +.RS +.TP +.B write (default) +Write opcodes are issued as usual +.TP +.B verify +Issue WRITE AND VERIFY commands. The BYTCHK bit is set to 0. This +directs the device to carry out a medium verification with no data +comparison. The writefua option is ignored with this selection. +.TP +.B same +Issue WRITE SAME commands. This transfers a single block to the device +and writes this same block of data to a contiguous sequence of LBAs +beginning at the specified offset. fio's block size parameter +specifies the amount of data written with each command. However, the +amount of data actually transferred to the device is equal to the +device's block (sector) size. For a device with 512 byte sectors, +blocksize=8k will write 16 sectors with each command. fio will still +generate 8k of data for each command butonly the first 512 bytes will +be used and transferred to the device. The writefua option is ignored +with this selection. + .SS "I/O depth" .TP .BI iodepth \fR=\fPint @@ -2028,6 +2057,11 @@ to replay a workload captured by blktrace. See replay, the file needs to be turned into a blkparse binary data file first (`blkparse \-o /dev/null \-d file_for_fio.bin'). .TP +.BI read_iolog_chunked \fR=\fPbool +Determines how iolog is read. If false (default) entire \fBread_iolog\fR will +be read at once. If selected true, input from iolog will be read gradually. +Useful when iolog is very large, or it is generated. +.TP .BI replay_no_stall \fR=\fPbool When replaying I/O with \fBread_iolog\fR the default behavior is to attempt to respect the timestamps within the log and replay them with the @@ -2067,6 +2101,12 @@ value. Scale sector offsets down by this factor when replaying traces. .SS "Threads, processes and job synchronization" .TP +.BI replay_skip \fR=\fPstr +Sometimes it's useful to skip certain IO types in a replay trace. This could +be, for instance, eliminating the writes in the trace. Or not replaying the +trims/discards, if you are redirecting to a device that doesn't support them. +This option takes a comma separated list of read, write, trim, sync. +.TP .BI thread Fio defaults to creating jobs by using fork, however if this option is given, fio will create jobs by using POSIX Threads' function @@ -2338,18 +2378,13 @@ that the written data is also correctly read back. If the data direction given is a read or random read, fio will assume that it should verify a previously written file. If the data direction includes any form of write, the verify will be of the newly written data. +.P +To avoid false verification errors, do not use the norandommap option when +verifying data with async I/O engines and I/O depths > 1. Or use the +norandommap and the lfsr random generator together to avoid writing to the +same offset with muliple outstanding I/Os. .RE .TP -.BI verifysort \fR=\fPbool -If true, 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 I/O where -the red\-black tree sorting CPU time becomes significant. Default: true. -.TP -.BI verifysort_nr \fR=\fPint -Pre\-load and sort verify blocks for a read workload. -.TP .BI verify_offset \fR=\fPint Swap the verification header with data somewhere else in the block before writing. It is swapped back before verifying.