Restore BUSY_OK bypassing of bitmap

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index a7bd1fb07da4a9ad872e054958ee39514fadc0dc..6391b82a9c79b31fe3e3b0f2fac2dd0b6caf57ae 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -716,6 +716,25 @@ rwmixwrite=int     How large a percentage of the mix should be writes. If both
                if fio is asked to limit reads or writes to a certain rate.
                If that is the case, then the distribution may be skewed.
 
+random_distribution=str: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:
+
+               random          Uniform random distribution
+               zipf            Zipf distribution
+               pareto          Pareto distribution
+
+               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.
+
 norandommap    Normally fio will cover every block of the file when doing
                random IO. If this option is given, fio will just get a
                new random offset without looking at past io history. This
@@ -1385,7 +1404,7 @@ Idle      Run
 ----    ---
 P              Thread setup, but not started.
 C              Thread created.
-I              Thread initialized, waiting.
+I              Thread initialized, waiting or generating necessary data.
        p       Thread running pre-reading file(s).
        R       Running, doing sequential reads.
        r       Running, doing random reads.