docs: move rate_cycle description

[fio.git] / HOWTO.rst

diff --git a/HOWTO.rst b/HOWTO.rst
index bbd9496eefb37f952e3dea1f76adbd2df54a2e76..8d4c6e1cca48324cb7a566ae795cfe0351181027 100644 (file)
--- a/HOWTO.rst
+++ b/HOWTO.rst
@@ -1232,13 +1232,12 @@ I/O type
 
 .. option:: randrepeat=bool
 
-       Seed the random number generator used for random I/O patterns in a
-       predictable way so the pattern is repeatable across runs. Default: true.
+        Seed all random number generators in a predictable way so the pattern
+        is repeatable across runs. Default: true.
 
 .. option:: allrandrepeat=bool
 
-       Seed all random number generators in a predictable way so results are
-       repeatable across runs.  Default: false.
+       Alias for :option:`randrepeat`. Default: true.
 
 .. option:: randseed=int
 
@@ -1308,6 +1307,11 @@ I/O type
                **random**
                        Advise using **FADV_RANDOM**.
 
+               **noreuse**
+                       Advise using **FADV_NOREUSE**. This may be a no-op on older Linux
+                       kernels. Since Linux 6.3, it provides a hint to the LRU algorithm.
+                       See the :manpage:`posix_fadvise(2)` man page.
+
 .. option:: write_hint=str
 
        Use :manpage:`fcntl(2)` to advise the kernel what life time to expect
@@ -3199,6 +3203,11 @@ I/O rate
        fio will ignore the thinktime and continue doing IO at the specified
        rate, instead of entering a catch-up mode after thinktime is done.
 
+.. option:: rate_cycle=int
+
+       Average bandwidth for :option:`rate` and :option:`rate_min` over this number
+       of milliseconds. Defaults to 1000.
+
 
 I/O latency
 ~~~~~~~~~~~
@@ -3237,11 +3246,6 @@ I/O latency
        microseconds. Comma-separated values may be specified for reads, writes,
        and trims as described in :option:`blocksize`.
 
-.. option:: rate_cycle=int
-
-       Average bandwidth for :option:`rate` and :option:`rate_min` over this number
-       of milliseconds. Defaults to 1000.
-
 
 I/O replay
 ~~~~~~~~~~
@@ -3821,10 +3825,11 @@ Steady state
 
 .. option:: steadystate_duration=time, ss_dur=time
 
-       A rolling window of this duration will be used to judge whether steady state
-       has been reached. Data will be collected once per second. The default is 0
-       which disables steady state detection.  When the unit is omitted, the
-       value is interpreted in seconds.
+        A rolling window of this duration will be used to judge whether steady
+        state has been reached. Data will be collected every
+        :option:`ss_interval`.  The default is 0 which disables steady state
+        detection.  When the unit is omitted, the value is interpreted in
+        seconds.
 
 .. option:: steadystate_ramp_time=time, ss_ramp=time
 
@@ -3832,6 +3837,14 @@ Steady state
        collection for checking the steady state job termination criterion. The
        default is 0.  When the unit is omitted, the value is interpreted in seconds.
 
+.. option:: steadystate_check_interval=time, ss_interval=time
+
+        The values during the rolling window will be collected with a period of
+        this value. If :option:`ss_interval` is 30s and :option:`ss_dur` is
+        300s, 10 measurements will be taken. Default is 1s but that might not
+        converge, especially for slower devices, so set this accordingly. When
+        the unit is omitted, the value is interpreted in seconds.
+
 
 Measurements and reporting
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -4404,15 +4417,23 @@ writes in the example above).  In the order listed, they denote:
                 It is the sum of submission and completion latency.
 
 **bw**
-               Bandwidth statistics based on samples. Same names as the xlat stats,
-               but also includes the number of samples taken (**samples**) and an
-               approximate percentage of total aggregate bandwidth this thread
-               received in its group (**per**). This last value is only really
-               useful if the threads in this group are on the same disk, since they
-               are then competing for disk access.
+               Bandwidth statistics based on measurements from discrete
+               intervals. Fio continuously monitors bytes transferred and I/O
+               operations completed. By default fio calculates bandwidth in
+               each half-second interval (see :option:`bwavgtime`) and reports
+               descriptive statistics for the measurements here. Same names as
+               the xlat stats, but also includes the number of samples taken
+               (**samples**) and an approximate percentage of total aggregate
+               bandwidth this thread received in its group (**per**). This
+               last value is only really useful if the threads in this group
+               are on the same disk, since they are then competing for disk
+               access.
 
 **iops**
-               IOPS statistics based on samples. Same names as bw.
+               IOPS statistics based on measurements from discrete intervals.
+               For details see the description for bw above. See
+               :option:`iopsavgtime` to control the duration of the intervals.
+               Same values reported here as for bw except for percentage.
 
 **lat (nsec/usec/msec)**
                The distribution of I/O completion latencies. This is the time from when