X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=HOWTO;h=ffdcb755f1a25a0f41158ae2767826a3ec910ac8;hb=9e55f2c7debac6683b1c41ce1f816ed868396798;hp=c2c65096bbd22461590c502aba6771b26598f672;hpb=21c1b29e929c2875f6dba7dfb6b0cc061f3730b5;p=fio.git

diff --git a/HOWTO b/HOWTO
index c2c65096..ffdcb755 100644
--- 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 lower value specified happens to be larger than the upper value,
+	two values are swapped.
 
 .. _bool:
 
@@ -886,7 +888,8 @@ Target file/device
 	If this isn't set, fio will abort jobs that are destructive (e.g. that write)
 	to what appears to be a mounted device or partition. This should help catch
 	creating inadvertently destructive tests, not realizing that the test will
-	destroy data on the mounted file system. Default: false.
+	destroy data on the mounted file system. Note that some platforms don't allow
+	writing against a mounted device regardless of this option. Default: false.
 
 .. option:: pre_read=bool
 
@@ -1099,13 +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
-	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)`.
+	Defaults to 0, which means no sync data every certain number of writes.
 
 .. option:: write_barrier=int
 
@@ -1570,6 +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.
+			See :option:`fsync` and :option:`fdatasync` for syncing write I/Os.
 
 		**psync**
 			Basic :manpage:`pread(2)` or :manpage:`pwrite(2)` I/O.  Default on
@@ -1669,6 +1675,11 @@ I/O engine
 			DDIR_TRIM
 				does fallocate(,mode = FALLOC_FL_KEEP_SIZE|FALLOC_FL_PUNCH_HOLE).
 
+		**ftruncate**
+			I/O engine that sends :manpage:`ftruncate(2)` operations in response
+			to write (DDIR_WRITE) events. Each ftruncate issued sets the file's
+			size to the current block offset. Block size is ignored.
+
 		**e4defrag**
 			I/O engine that does regular EXT4_IOC_MOVE_EXT ioctls to simulate
 			defragment activity in request to DDIR_WRITE event.
@@ -1747,7 +1758,8 @@ caveat that when used on the command line, they must come after the
 
 .. 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]
 
@@ -2592,6 +2604,12 @@ Measurements and reporting
 	all jobs in a file will be part of the same reporting group, unless
 	separated by a :option:`stonewall`.
 
+.. option:: stats
+
+	By default, fio collects and shows final output results for all jobs
+	that run. If this option is set to 0, then fio will ignore it in
+	the final stat output.
+
 .. option:: write_bw_log=str
 
 	If given, write a bandwidth log for this job. Can be used to store data of