From c35dd7a6ce7bed8a5345c69e7b5499c71908d21c Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 10 Jun 2009 08:39:16 +0200 Subject: [PATCH 1/1] Documentation update Signed-off-by: Jens Axboe --- HOWTO | 4 +++- fio.1 | 29 ++++++++++++++++++++--------- 2 files changed, 23 insertions(+), 10 deletions(-) diff --git a/HOWTO b/HOWTO index 8f732083..2be845c4 100644 --- a/HOWTO +++ b/HOWTO @@ -546,7 +546,9 @@ rwmixread=int How large a percentage of the mix should be reads. rwmixwrite=int How large a percentage of the mix should be writes. If both rwmixread and rwmixwrite is given and the values do not add up to 100%, the latter of the two will be used to override - the first. + 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. norandommap Normally fio will cover every block of the file when doing random IO. If this option is given, fio will just get a diff --git a/fio.1 b/fio.1 index a897d279..2bf2c2f7 100644 --- a/fio.1 +++ b/fio.1 @@ -346,8 +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 @@ -376,18 +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 @@ -415,8 +426,8 @@ as \fBruntime\fR allows. 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 ramp_time is considered lead in time for a job, thus it will increase -the total runtime if a special timeout or runtime is specified. +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. -- 2.25.1