X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=45a96bb1618182c0251fb8a77a4bdfd1ab6e460b;hp=bc23052d61e568434b23488c150e525d0ee48407;hb=ba3e4e0ca697f83c97a250d85a74506ace69de2c;hpb=7c353ceb3257b132f4c98326046b42201e070731

diff --git a/HOWTO b/HOWTO
index bc23052d..45a96bb1 100644
--- a/HOWTO
+++ b/HOWTO
@@ -158,6 +158,9 @@ specify:
 
 $ fio --name=random-writers --ioengine=libaio --iodepth=4 --rw=randwrite --bs=32k --direct=0 --size=64m --numjobs=4
 
+4.1 Environment variables
+-------------------------
+
 fio also supports environment variable expansion in job files. Any
 substring of the form "${VARNAME}" as part of an option value (in other
 words, on the right of the `='), will be expanded to the value of the
@@ -188,6 +191,26 @@ numjobs=4
 fio ships with a few example job files, you can also look there for
 inspiration.
 
+4.2 Reserved keywords
+---------------------
+
+Additionally, fio has a set of reserved keywords that will be replaced
+internally with the appropriate value. Those keywords are:
+
+$pagesize	The architecture page size of the running system
+$mb_memory	Megabytes of total memory in the system
+$ncpus		Number of online available CPUs
+
+These can be used on the command line or in the job file, and will be
+automatically substituted with the current system values when the job
+is run. Simple math is also supported on these keywords, so you can
+perform actions like:
+
+size=8*$mb_memory
+
+and get that properly expanded to 8 times the size of memory in the
+machine.
+
 
 5.0 Detailed list of parameters
 -------------------------------
@@ -806,7 +829,11 @@ verify=str	If writing to a file, fio can verify the file contents
 
 		This option can be used for repeated burn-in tests of a
 		system to make sure that the written data is also
-		correctly read back.
+		correctly read back. If the data direction given is
+		a read or random read, fio will assume that it should
+		verify a previously written file. If the data direction
+		includes any form of write, the verify will be of the
+		newly written data.
 
 verifysort=bool	If set, fio will sort written verify blocks when it deems
 		it faster to read them back in a sorted manner. This is
@@ -825,13 +852,14 @@ verify_interval=int	Write the verification header at a finer granularity
 			size of header_interval. blocksize should divide this
 			evenly.
 
-verify_pattern=int	If set, fio will fill the io buffers with this
+verify_pattern=str	If set, fio will fill the io buffers with this
 		pattern. Fio defaults to filling with totally random
 		bytes, but sometimes it's interesting to fill with a known
 		pattern for io verification purposes. Depending on the
 		width of the pattern, fio will fill 1/2/3/4 bytes of the
-		buffer at the time. The verify_pattern cannot be larger than
-		a 32-bit quantity.
+		buffer at the time(it can be either a decimal or a hex number).
+		The verify_pattern if larger than a 32-bit quantity has to
+		be a hex number that starts with either "0x" or "0X".
 
 verify_fatal=bool	Normally fio will keep checking the entire contents
 		before quitting on a block verification failure. If this
@@ -966,6 +994,7 @@ gtod_cpu=int	Sometimes it's cheaper to dedicate a single thread of
 		for doing these time calls will be excluded from other
 		uses. Fio will manually clear it from the CPU mask of other
 		jobs.
+
 continue_on_error=bool	Normally fio will exit the job on the first observed
 		failure. If this option is set, fio will continue the job when
 		there is a 'non-fatal error' (EIO or EILSEQ) until the runtime
@@ -975,6 +1004,21 @@ continue_on_error=bool	Normally fio will exit the job on the first observed
 		given in the stats is the first error that was hit during the
 		run.
 
+cgroup=str	Add job to this control group. If it doesn't exist, it will
+		be created. The system must have a mounted cgroup blkio
+		mount point for this to work. If your system doesn't have it
+		mounted, you can do so with:
+
+		# mount -t cgroup -o blkio none /cgroup
+
+cgroup_weight=int	Set the weight of the cgroup to this value. See
+		the documentation that comes with the kernel, allowed values
+		are in the range of 100..1000.
+
+uid=int		Instead of running as the invoking user, set the user ID to
+		this value before the thread/process does any work.
+
+gid=int		Set group ID, see uid.
 
 6.0 Interpreting the output
 ---------------------------