X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=3af491325d3324b69117cc946728d7cd23ab8060;hp=167ed7c7f0adb472f186bee73d8d0d364e1484f3;hb=244e170ebd309303d124c57cde7bf7a3b40d09e7;hpb=6df8adaaadb71340b47f2c3e971297b656082ca5

diff --git a/HOWTO b/HOWTO
index 167ed7c7..3af49132 100644
--- a/HOWTO
+++ b/HOWTO
@@ -170,7 +170,7 @@ Some parameters take an option of a given type, such as an integer or
 a string. The following types are used:
 
 str	String. This is a sequence of alpha characters.
-int	Integer. A whole number value, may be negative.
+int	Integer. A whole number value, can be negative.
 siint	SI integer. A whole number value, which may contain a postfix
 	describing the base of the number. Accepted postfixes are k/m/g,
 	meaning kilo, mega, and giga. So if you want to specify 4096,
@@ -249,12 +249,12 @@ fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
 		If set, fio will use POSIX_FADV_SEQUENTIAL for sequential
 		IO and POSIX_FADV_RANDOM for random IO.
 
-size=siint	The total size of file io for this job. This may describe
-		the size of the single file the job uses, or it may be
-		divided between the number of files in the job. If the
-		file already exists, the file size will be adjusted to this
-		size if larger than the current file size. If this parameter
-		is not given and the file exists, the file size will be used.
+size=siint	The total size of file io for this job. Fio will run until
+		this many bytes has been transferred, unless runtime is
+		limited by other options (such as 'runtime', for instance).
+		Unless specific nr_files and filesize options are given,
+		fio will divide this size between the available files
+		specified by the job.
 
 filesize=siint	Individual file sizes. May be a range, in which case fio
 		will select sizes for files at random within the given range
@@ -343,6 +343,9 @@ ioengine=str	Defines how the job issues io to the file. The following
 				or receive, if the latter only the port
 				argument is used.
 
+			netsplice Like net, but uses splice/vmsplice to
+				map data and send/receive.
+
 			cpu	Doesn't transfer any data, but burns CPU
 				cycles according to the cpuload= and
 				cpucycle= options. Setting cpuload=85
@@ -419,7 +422,9 @@ norandommap	Normally fio will cover every block of the file when doing
 		new random offset without looking at past io history. This
 		means that some blocks may not be read or written, and that
 		some blocks may be read/written more than once. This option
-		is mutually exclusive with verify= for that reason.
+		is mutually exclusive with verify= for that reason, since
+		fio doesn't track potential block rewrites which may alter
+		the calculated checksum for that block.
 
 nice=int	Run the job with the given nice value. See man nice(2).
 
@@ -464,8 +469,15 @@ ratecycle=int	Average bandwidth for 'rate' and 'ratemin' over this number
 		of milliseconds.
 
 cpumask=int	Set the CPU affinity of this job. The parameter given is a
-		bitmask of allowed CPU's the job may run on. See man
-		sched_setaffinity(2).
+		bitmask of allowed CPU's the job may run on. So if you want
+		the allowed CPUs to be 1 and 5, you would pass the decimal
+		value of (1 << 1 | 1 << 5), or 34. See man
+		sched_setaffinity(2). This may not work on all supported
+		operating systems or kernel versions.
+
+cpus_allowed=str Controls the same options as cpumask, but it allows a text
+		setting of the permitted CPUs instead. So to use CPUs 1 and
+		5, you would specify cpus_allowed=1,5.
 
 startdelay=int	Start this job the specified number of seconds after fio
 		has started. Only useful if the job file contains several
@@ -714,7 +726,10 @@ runt=		The runtime of that thread
 	slat=	Submission latency (avg being the average, stdev being the
 		standard deviation). This is the time it took to submit
 		the io. For sync io, the slat is really the completion
-		latency, since queue/complete is one operation there.
+		latency, since queue/complete is one operation there. This
+		value can be in miliseconds or microseconds, fio will choose
+		the most appropriate base and print that. In the example
+		above, miliseconds is the best scale.
 	clat=	Completion latency. Same names as slat, this denotes the
 		time from submission to completion of the io pieces. For
 		sync io, clat will usually be equal (or very close) to 0,