X-Git-Url: https://git.kernel.dk/?a=blobdiff_plain;f=HOWTO;h=4c117c2473d6693158f1b3f346387d342b8d55bd;hb=0777612739319296ee25047c1bdb56207187c463;hp=4d905d16f3ecda61adebdc3910015077bd4629e1;hpb=77be374dc96e9155b6c039a776a364798432549e;p=fio.git

diff --git a/HOWTO b/HOWTO
index 4d905d16..4c117c24 100644
--- a/HOWTO
+++ b/HOWTO
@@ -283,7 +283,8 @@ Command line options
 
 .. option:: --aux-path=path
 
-	Use this `path` for fio state generated files.
+	Use the directory specified by `path` for generated state files instead
+	of the current working directory.
 
 Any parameters following the options will be assumed to be job files, unless
 they match a job file parameter. Multiple job files can be listed and each job
@@ -748,12 +749,15 @@ Target file/device
 	assigned equally distributed to job clones created by :option:`numjobs` as
 	long as they are using generated filenames. If specific `filename(s)` are
 	set fio will use the first listed directory, and thereby matching the
-	`filename` semantic which generates a file each clone if not specified, but
-	let all clones use the same if set.
+	`filename` semantic (which generates a file for each clone if not
+	specified, but lets all clones use the same file if set).
 
 	See the :option:`filename` option for information on how to escape "``:``" and
 	"``\``" characters within the directory path itself.
 
+	Note: To control the directory fio will use for internal state files
+	use :option:`--aux-path`.
+
 .. option:: filename=str
 
 	Fio normally makes up a `filename` based on the job name, thread number, and
@@ -991,13 +995,15 @@ I/O type
 		**write**
 				Sequential writes.
 		**trim**
-				Sequential trims (Linux block devices only).
+				Sequential trims (Linux block devices and SCSI
+				character devices only).
 		**randread**
 				Random reads.
 		**randwrite**
 				Random writes.
 		**randtrim**
-				Random trims (Linux block devices only).
+				Random trims (Linux block devices and SCSI
+				character devices only).
 		**rw,readwrite**
 				Sequential mixed reads and writes.
 		**randrw**
@@ -1748,7 +1754,7 @@ I/O engine
 			ioctl, or if the target is an sg character device we use
 			:manpage:`read(2)` and :manpage:`write(2)` for asynchronous
 			I/O. Requires :option:`filename` option to specify either block or
-			character devices.
+			character devices. This engine supports trim operations.
 			The sg engine includes engine specific options.
 
 		**null**
@@ -2082,6 +2088,7 @@ with the caveat that when used on the command line, they must come after the
 	the force unit access (fua) flag. Default is 0.
 
 .. option:: sg_write_mode=str : [sg]
+
 	Specify the type of write commands to issue. This option can take three values:
 
 	**write**
@@ -2912,9 +2919,11 @@ Measurements and reporting
 .. option:: write_iops_log=str
 
 	Same as :option:`write_bw_log`, but writes an IOPS file (e.g.
-	:file:`name_iops.x.log`) instead. See :option:`write_bw_log` for
-	details about the filename format and `Log File Formats`_ for how data
-	is structured within the file.
+	:file:`name_iops.x.log`) instead. Because fio defaults to individual
+	I/O logging, the value entry in the IOPS log will be 1 unless windowed
+	logging (see :option:`log_avg_msec`) has been enabled. See
+	:option:`write_bw_log` for details about the filename format and `Log
+	File Formats`_ for how data is structured within the file.
 
 .. option:: log_avg_msec=int
 
@@ -3799,17 +3808,16 @@ on the type of log, it will be one of the following:
 	**2**
 		I/O is a TRIM
 
-The entry's *block size* is always in bytes. The *offset* is the offset, in bytes,
-from the start of the file, for that particular I/O. The logging of the offset can be
+The entry's *block size* is always in bytes. The *offset* is the position in bytes
+from the start of the file for that particular I/O. The logging of the offset can be
 toggled with :option:`log_offset`.
 
-Fio defaults to logging every individual I/O.  When IOPS are logged for individual
-I/Os the *value* entry will always be 1. If windowed logging is enabled through
-:option:`log_avg_msec`, fio logs the average values over the specified period of time.
-If windowed logging is enabled and :option:`log_max_value` is set, then fio logs
-maximum values in that window instead of averages. Since *data direction*, *block
-size* and *offset* are per-I/O values, if windowed logging is enabled they
-aren't applicable and will be 0.
+Fio defaults to logging every individual I/O but when windowed logging is set
+through :option:`log_avg_msec`, either the average (by default) or the maximum
+(:option:`log_max_value` is set) *value* seen over the specified period of time
+is recorded. Each *data direction* seen within the window period will aggregate
+its values in a separate row. Further, when using windowed logging the *block
+size* and *offset* entries will always contain 0.
 
 Client/Server
 -------------