X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=fio.1;h=22c32fd0f59c1deeba9b96bd3f563064485c7b52;hb=60f32acb9b1cafd9865d5ea36e5a8a63240a9074;hp=08d6c0f4ba3da66191ba855de21f60a4ed0b838c;hpb=155015351132ad00e2e21cb63f52fee91e56e92a;p=fio.git

diff --git a/fio.1 b/fio.1
index 08d6c0f4..22c32fd0 100644
--- a/fio.1
+++ b/fio.1
@@ -486,8 +486,8 @@ transfer as fio ioengine
 .B e4defrag
 IO engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate defragment activity
 request to DDIR_WRITE event
-.TP
 .RE
+.P
 .RE
 .TP
 .BI iodepth \fR=\fPint
@@ -580,6 +580,32 @@ 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
+.BI random_distribution \fR=\fPstr:float
+By default, fio will use a completely uniform random distribution when asked
+to perform random IO. Sometimes it is useful to skew the distribution in
+specific ways, ensuring that some parts of the data is more hot than others.
+Fio includes the following distribution models:
+.RS
+.TP
+.B random
+Uniform random distribution
+.TP
+.B zipf
+Zipf distribution
+.TP
+.B pareto
+Pareto distribution
+.TP
+.RE
+.P
+When using a zipf or pareto distribution, an input value is also needed to
+define the access pattern. For zipf, this is the zipf theta. For pareto,
+it's the pareto power. Fio includes a test program, genzipf, that can be
+used visualize what the given input values will yield in terms of hit rates.
+If you wanted to use zipf with a theta of 1.2, you would use
+random_distribution=zipf:1.2 as the option. If a non-uniform model is used,
+fio will disable use of the random map.
+.TP
 .B norandommap
 Normally \fBfio\fR will cover every block of the file when doing random I/O. If
 this parameter is given, a new offset will be chosen without looking at past
@@ -591,6 +617,26 @@ fails to allocate the map, if this option is set it will continue without a
 random block map. As coverage will not be as complete as with random maps, this
 option is disabled by default.
 .TP
+.BI random_generator \fR=\fPstr
+Fio supports the following engines for generating IO offsets for random IO:
+.RS
+.TP
+.B tausworthe
+Strong 2^88 cycle random number generator
+.TP
+.B lfsr
+Linear feedback shift register generator
+.TP
+.RE
+.P
+Tausworthe is a strong random number generator, but it requires tracking on the
+side if we want to ensure that blocks are only read or written once. LFSR
+guarantees that we never generate the same offset twice, and it's also less
+computationally expensive. It's not a true random generator, however, though
+for IO purposes it's typically good enough. LFSR only works with single block
+sizes, not with workloads that use multiple block sizes. If used with such a
+workload, fio may read or write some blocks multiple times.
+.TP
 .BI nice \fR=\fPint
 Run job with given nice value.  See \fInice\fR\|(2).
 .TP
@@ -981,6 +1027,27 @@ given time in milliseconds.
 .BI disk_util \fR=\fPbool
 Generate disk utilization statistics if the platform supports it. Default: true.
 .TP
+.BI clocksource \fR=\fPstr
+Use the given clocksource as the base of timing. The supported options are:
+.RS
+.TP
+.B gettimeofday
+gettimeofday(2)
+.TP
+.B clock_gettime
+clock_gettime(2)
+.TP
+.B cpu
+Internal CPU clock source
+.TP
+.RE
+.P
+\fBcpu\fR is the preferred clocksource if it is reliable, as it is very fast
+(and fio is heavy on time calls). Fio will automatically use this clocksource
+if it's supported and considered reliable on the system it is running on,
+unless another clocksource is specifically set. For x86/x86-64 CPUs, this
+means supporting TSC Invariant.
+.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
@@ -1116,6 +1183,15 @@ For TCP network connections, tell fio to listen for incoming
 connections rather than initiating an outgoing connection. The
 hostname must be omitted if this option is used.
 .TP
+.BI (net, pingpong) \fR=\fPbool
+Normal a network writer will just continue writing data, and a network reader
+will just consume packages. If pingpong=1 is set, a writer will send its normal
+payload to the reader, then wait for the reader to send the same payload back.
+This allows fio to measure network latencies. The submission and completion
+latencies then measure local time spent sending or receiving, and the
+completion latency measures how long it took for the other end to receive and
+send back.
+.TP
 .BI (e4defrag,donorname) \fR=\fPstr
 File will be used as a block donor (swap extents between files)
 .TP