HOWTO: Mention niche detail of range format options

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 5d378f3d9a75cf7c0e1cd7ca95f65ecaee060d58..80b9e75a75cf52ba86b38f6e1addea8f4a118b52 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -543,6 +543,8 @@ Parameter types
 
        If the option accepts an upper and lower range, use a colon ':' or
        minus '-' to separate such values. See :ref:`irange <irange>`.
 
        If the option accepts an upper and lower range, use a colon ':' or
        minus '-' to separate such values. See :ref:`irange <irange>`.

+       If the lower value specified happens to be larger than the upper value,
+       two values are swapped.

 
 .. _bool:
 
 
 .. _bool:
 


@@ -1100,13 +1102,15 @@ I/O type
        blocks given. For example, if you give 32 as a parameter, fio will sync the
        file for every 32 writes issued. If fio is using non-buffered I/O, we may
        not sync the file. The exception is the sg I/O engine, which synchronizes
        blocks given. For example, if you give 32 as a parameter, fio will sync the
        file for every 32 writes issued. If fio is using non-buffered I/O, we may
        not sync the file. The exception is the sg I/O engine, which synchronizes

-       the disk cache anyway.
+       the disk cache anyway. Defaults to 0, which means no sync every certain
+       number of writes.

 
 .. option:: fdatasync=int
 
        Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
        not metadata blocks.  In Windows, FreeBSD, and DragonFlyBSD there is no
        :manpage:`fdatasync(2)`, this falls back to using :manpage:`fsync(2)`.
 
 .. option:: fdatasync=int
 
        Like :option:`fsync` but uses :manpage:`fdatasync(2)` to only sync data and
        not metadata blocks.  In Windows, FreeBSD, and DragonFlyBSD there is no
        :manpage:`fdatasync(2)`, this falls back to using :manpage:`fsync(2)`.

+       Defaults to 0, which means no sync data every certain number of writes.

 
 .. option:: write_barrier=int
 
 
 .. option:: write_barrier=int
 


@@ -1571,6 +1575,7 @@ I/O engine
                **sync**
                        Basic :manpage:`read(2)` or :manpage:`write(2)`
                        I/O. :manpage:`lseek(2)` is used to position the I/O location.
                **sync**
                        Basic :manpage:`read(2)` or :manpage:`write(2)`
                        I/O. :manpage:`lseek(2)` is used to position the I/O location.

+                       See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.

 
                **psync**
                        Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O.  Default on
 
                **psync**
                        Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O.  Default on


@@ -1748,7 +1753,8 @@ caveat that when used on the command line, they must come after the
 
 .. option:: cpuload=int : [cpuio]
 
 
 .. option:: cpuload=int : [cpuio]
 

-       Attempt to use the specified percentage of CPU cycles.
+       Attempt to use the specified percentage of CPU cycles. This is a mandatory
+       option when using cpuio I/O engine.

 
 .. option:: cpuchunks=int : [cpuio]
 
 
 .. option:: cpuchunks=int : [cpuio]