X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=76effeef9e1b2bc2c9d0254301a9c9042dd50692;hp=8073240ef14074b5007bafa4296b913f1951f647;hb=de98bd30b02bd89a78059d162b2c8426e889703d;hpb=771e58befea806d2d881953050c4e65329eee382

diff --git a/HOWTO b/HOWTO
index 8073240e..76effeef 100644
--- a/HOWTO
+++ b/HOWTO
@@ -9,6 +9,7 @@ Table of contents
 6. Normal output
 7. Terse output
 8. Trace file format
+9. CPU idleness profiling
 
 1.0 Overview and history
 ------------------------
@@ -284,6 +285,32 @@ filename=str	Fio normally makes up a filename based on the job name,
 		stdin or stdout. Which of the two depends on the read/write
 		direction set.
 
+filename_format=str
+		If sharing multiple files between jobs, it is usually necessary
+		to  have fio generate the exact names that you want. By default,
+		fio will name a file based on the default file format
+		specification of jobname.jobnumber.filenumber. With this
+		option, that can be customized. Fio will recognize and replace
+		the following keywords in this string:
+
+		$jobname
+			The name of the worker thread or process.
+
+		$jobnum
+			The incremental number of the worker thread or
+			process.
+
+		$filenum
+			The incremental number of the file for that worker
+			thread or process.
+
+		To have dependent jobs share a set of files, this option can
+		be set to have fio generate filenames that are shared between
+		the two. For instance, if testfiles.$filenum is specified,
+		file number 4 for any job will be named testfiles.4. The
+		default of $jobname.$jobnum.$filenum will be used if
+		no other format specifier is given.
+
 opendir=str	Tell fio to recursively add any file it can find in this
 		directory and down the file system tree.
 
@@ -301,11 +328,6 @@ lockfile=str	Fio defaults to not locking any files before it does
 					same time, but writes get exclusive
 					access.
 
-		The option may be post-fixed with a lock batch number. If
-		set, then each thread/process may do that amount of IOs to
-		the file before giving up the lock. Since lock acquisition is
-		expensive, batching the lock/unlocks will speed up IO.
-
 readwrite=str
 rw=str		Type of io pattern. Accepted values are:
 
@@ -409,7 +431,7 @@ filesize=int	Individual file sizes. May be a range, in which case fio
 fill_device=bool
 fill_fs=bool	Sets size to something really large and waits for ENOSPC (no
 		space left on device) as the terminating condition. Only makes
-                sense with sequential write. For a read workload, the mount
+		sense with sequential write. For a read workload, the mount
 		point will be filled first then IO started on the result. This
 		option doesn't make sense if operating on a raw device node,
 		since the size of that is already known by the file system.
@@ -775,7 +797,7 @@ random_generator=str	Fio supports the following engines for generating
 		block sizes, not with workloads that use multiple block
 		sizes. If used with such a workload, fio may read or write
 		some blocks multiple times.
-		
+
 nice=int	Run the job with the given nice value. See man nice(2).
 
 prio=int	Set the io priority value of this job. Linux limits us to
@@ -1402,6 +1424,9 @@ that defines them is selected.
 [netsplice] port=int
 [net] port=int	The TCP or UDP port to bind to or connect to.
 
+[netsplice] nodelay=bool
+[net] nodelay=bool	Set TCP_NODELAY on TCP connections.
+
 [netsplice] protocol=str
 [netsplice] proto=str
 [net] protocol=str
@@ -1693,3 +1718,18 @@ write      Write 'length' bytes beginning from 'offset'
 sync       fsync() the file
 datasync   fdatasync() the file
 trim       trim the given file from the given 'offset' for 'length' bytes
+
+
+9.0 CPU idleness profiling
+
+In some cases, we want to understand CPU overhead in a test. For example,
+we test patches for the specific goodness of whether they reduce CPU usage.
+fio implements a balloon approach to create a thread per CPU that runs at
+idle priority, meaning that it only runs when nobody else needs the cpu.
+By measuring the amount of work completed by the thread, idleness of each
+CPU can be derived accordingly.
+
+An unit work is defined as touching a full page of unsigned characters. Mean
+and standard deviation of time to complete an unit work is reported in "unit
+work" section. Options can be chosen to report detailed percpu idleness or
+overall system idleness by aggregating percpu stats.