X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=fio.1;h=2bf2c2f77a8fd9e2b7cdd4230776aebd947b1b62;hp=2eb445578122bb993a5be6569a214e37e7c95743;hb=c35dd7a6ce7bed8a5345c69e7b5499c71908d21c;hpb=6b7f68516d785163bf76565c1635012f66b9f51f diff --git a/fio.1 b/fio.1 index 2eb44557..2bf2c2f7 100644 --- a/fio.1 +++ b/fio.1 @@ -187,15 +187,31 @@ block sizes for exact control of the issued IO for a job that has mixed block sizes. The format of the option is bssplit=blocksize/percentage, optionally adding as many definitions as needed seperated by a colon. Example: bssplit=4k/10:64k/50:32k/40 would issue 50% 64k blocks, 10% 4k -blocks and 40% 32k blocks. +blocks and 40% 32k blocks. \fBbssplit\fR also supports giving separate +splits to reads and writes. The format is identical to what the +\fBbs\fR option accepts, the read and write parts are separated with a +comma. .TP .B blocksize_unaligned\fR,\fP bs_unaligned If set, any size in \fBblocksize_range\fR may be used. This typically won't work with direct I/O, as that normally requires sector alignment. .TP +.BI blockalign \fR=\fPint[,int] "\fR,\fB ba" \fR=\fPint[,int] +At what boundary to align random IO offsets. Defaults to the same as 'blocksize' +the minimum blocksize given. Minimum alignment is typically 512b +for using direct IO, though it usually depends on the hardware block size. +This option is mutually exclusive with using a random map for files, so it +will turn off that option. +.TP .B zero_buffers Initialise buffers with all zeros. Default: fill buffers with random data. .TP +.B 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 time and reuse that data. Only makes sense +if zero_buffers isn't specified, naturally. If data verification is enabled, +refill_buffers is also automatically enabled. +.TP .BI nrfiles \fR=\fPint Number of files to use for this job. Default: 1. .TP @@ -330,8 +346,10 @@ Percentage of a mixed workload that should be reads. Default: 50. .TP .BI rwmixwrite \fR=\fPint Percentage of a mixed workload that should be writes. If \fBrwmixread\fR and -\fBwrmixwrite\fR are given and do not sum to 100%, the latter of the two -overrides the first. Default: 50. +\fBrwmixwrite\fR are given and do not sum to 100%, the latter of the two +overrides the first. This may interfere with a given rate setting, if fio is +asked to limit reads or writes to a certain rate. If that is the case, then +the distribution may be skewed. Default: 50. .TP .B norandommap Normally \fBfio\fR will cover every block of the file when doing random I/O. If @@ -360,18 +378,27 @@ Number of blocks to issue before waiting \fBthinktime\fR microseconds. Default: 1. .TP .BI rate \fR=\fPint -Cap bandwidth used by this job to this number of KiB/s. +Cap bandwidth used by this job. The number is in bytes/sec, the normal postfix +rules apply. You can use \fBrate\fR=500k to limit reads and writes to 500k each, +or you can specify read and writes separately. Using \fBrate\fR=1m,500k would +limit reads to 1MB/sec and writes to 500KB/sec. Capping only reads or writes +can be done with \fBrate\fR=,500k or \fBrate\fR=500k,. The former will only +limit writes (to 500KB/sec), the latter will only limit reads. .TP .BI ratemin \fR=\fPint Tell \fBfio\fR to do whatever it can to maintain at least the given bandwidth. -Failing to meet this requirement will cause the job to exit. +Failing to meet this requirement will cause the job to exit. The same format +as \fBrate\fR is used for read vs write separation. .TP .BI rate_iops \fR=\fPint -Cap the bandwidth to this number of IOPS. If \fBblocksize\fR is a range, the -smallest block size is used as the metric. +Cap the bandwidth to this number of IOPS. Basically the same as rate, just +specified independently of bandwidth. The same format as \fBrate\fR is used for +read vs write seperation. If \fBblocksize\fR is a range, the smallest block +size is used as the metric. .TP .BI rate_iops_min \fR=\fPint -If this rate of I/O is not met, the job will exit. +If this rate of I/O is not met, the job will exit. The same format as \fBrate\fR +is used for read vs write seperation. .TP .BI ratecycle \fR=\fPint Average bandwidth for \fBrate\fR and \fBratemin\fR over this number of @@ -395,6 +422,13 @@ If given, run for the specified \fBruntime\fR duration even if the files are completely read or written. The same workload will be repeated as many times as \fBruntime\fR allows. .TP +.BI ramp_time \fR=\fPint +If set, fio will run the specified workload for this amount of time before +logging any performance numbers. Useful for letting performance settle before +logging results, thus minimizing the runtime required for stable results. Note +that the \fBramp_time\fR is considered lead in time for a job, thus it will +increase the total runtime if a special timeout or runtime is specified. +.TP .BI invalidate \fR=\fPbool Invalidate buffer-cache for the file prior to starting I/O. Default: true. .TP @@ -450,6 +484,11 @@ If true, serialize file creation for the jobs. Default: true. .BI create_on_open \fR=\fPbool If true, the files are not created until they are opened for IO by the job. .TP +.BI pre_read \fR=\fPbool +If this is given, files will be pre-read into memory before starting the given +IO operation. This will also clear the \fR \fBinvalidate\fR flag, since it is +pointless to pre-read and then drop the cache. +.TP .BI unlink \fR=\fPbool Unlink job files when done. Default: false. .TP @@ -534,11 +573,29 @@ Write the issued I/O patterns to the specified file. Replay the I/O patterns contained in the specified file generated by \fBwrite_iolog\fR, or may be a \fBblktrace\fR binary file. .TP -.B write_bw_log -If given, write bandwidth logs of the jobs in this file. +.B write_bw_log \fR=\fPstr +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 script uses gnuplot to turn these text files into nice +graphs. See \fBwrite_log_log\fR for behaviour of given filename. For this +option, the postfix is _bw.log. .TP .B write_lat_log -Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. +Same as \fBwrite_bw_log\fR, but writes I/O completion latencies. If no +filename is given with this option, the default filename of "jobname_type.log" +is used. Even if the filename is given, fio will still append the type of log. +.TP +.B disable_clat \fR=\fPbool +Disable measurements of completion latency numbers. Useful only for cutting +back the number of calls to gettimeofday, as that does impact performance at +really high IOPS rates. Note that to really get rid of a large amount of these +calls, this option must be used with disable_slat and disable_bw as well. +.TP +.B disable_slat \fR=\fPbool +Disable measurements of submission latency numbers. See \fBdisable_clat\fR. +.TP +.B disable_bw_measurement \fR=\fPbool +Disable measurements of throughput/bandwidth numbers. See \fBdisable_clat\fR. .TP .BI lockmem \fR=\fPint Pin the specified amount of memory with \fBmlock\fR\|(2). Can be used to @@ -563,6 +620,22 @@ given time in milliseconds. .TP .BI disk_util \fR=\fPbool Generate disk utilization statistics if the platform supports it. Default: true. +.TP +.BI gtod_reduce \fR=\fPbool +Enable all of the gettimeofday() reducing options (disable_clat, disable_slat, +disable_bw) plus reduce precision of the timeout somewhat to really shrink the +gettimeofday() call count. With this option enabled, we only do about 0.4% of +the gtod() calls we would have done if all time keeping was enabled. +.TP +.BI gtod_cpu \fR=\fPint +Sometimes it's cheaper to dedicate a single thread of execution to just getting +the current time. Fio (and databases, for instance) are very intensive on +gettimeofday() calls. With this option, you can set one CPU aside for doing +nothing but logging current time to a shared memory location. Then the other +threads/processes that run IO workloads need only copy that segment, instead of +entering the kernel with a gettimeofday() call. The CPU set aside for doing +these time calls will be excluded from other uses. Fio will manually clear it +from the CPU mask of other jobs. .SH OUTPUT While running, \fBfio\fR will display the status of the created jobs. For example: @@ -777,7 +850,7 @@ was written by Jens Axboe . This man page was written by Aaron Carroll based on documentation by Jens Axboe. .SH "REPORTING BUGS" -Report bugs to the \fBfio\fR mailing list . +Report bugs to the \fBfio\fR mailing list . See \fBREADME\fR. .SH "SEE ALSO" For further documentation see \fBHOWTO\fR and \fBREADME\fR.