tools: use /usr/bin/python2.7 as the interpreter

[fio.git] / fio.1

diff --git a/fio.1 b/fio.1
index b943db2289d66c87ced5bd3b7112cf9b580db8ab..96d8f1147da412380ace93492460906432c8fceb 100644 (file)
--- a/fio.1
+++ b/fio.1
@@ -113,6 +113,8 @@ All fio parser warnings are fatal, causing fio to exit with an error.
 .TP
 .BI \-\-max\-jobs \fR=\fPnr
 Set the maximum number of threads/processes to support to \fInr\fR.
+NOTE: On Linux, it may be necessary to increase the shared-memory limit
+(`/proc/sys/kernel/shmmax') if fio runs into errors while creating jobs.
 .TP
 .BI \-\-server \fR=\fPargs
 Start a backend server, with \fIargs\fR specifying what to listen to.
@@ -576,6 +578,12 @@ 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.
+.P
+If you specify a path then the directories will be created up to the main
+directory for the file.  So for example if you specify `a/b/c/$jobnum` then the
+directories a/b/c will be created before the file setup part of the job.  If you
+specify \fBdirectory\fR then the path will be relative that directory, otherwise
+it is treated as the absolute path.
 .RE
 .TP
 .BI unique_filename \fR=\fPbool
@@ -905,13 +913,19 @@ should be associated with them.
 .TP
 .BI offset \fR=\fPint
 Start I/O at the provided offset in the file, given as either a fixed size in
-bytes or a percentage. If a percentage is given, the next \fBblockalign\fR\-ed
-offset will be used. Data before the given offset will not be touched. This
+bytes or a percentage. If a percentage is given, the generated offset will be
+aligned to the minimum \fBblocksize\fR or to the value of \fBoffset_align\fR if
+provided. Data before the given offset will not be touched. This
 effectively caps the file size at `real_size \- offset'. Can be combined with
 \fBsize\fR to constrain the start and end range of the I/O workload.
 A percentage can be specified by a number between 1 and 100 followed by '%',
 for example, `offset=20%' to specify 20%.
 .TP
+.BI offset_align \fR=\fPint
+If set to non-zero value, the byte offset generated by a percentage \fBoffset\fR
+is aligned upwards to this value. Defaults to 0 meaning that a percentage
+offset is aligned to the minimum block size.
+.TP
 .BI offset_increment \fR=\fPint
 If this is provided, then the real offset becomes `\fBoffset\fR + \fBoffset_increment\fR
 * thread_number', where the thread number is a counter that starts at 0 and
@@ -1577,6 +1591,10 @@ the engine filename, e.g. `ioengine=external:/tmp/foo.o' to load
 ioengine `foo.o' in `/tmp'. The path can be either
 absolute or relative. See `engines/skeleton_external.c' in the fio source for
 details of writing an external I/O engine.
+.TP
+.B filecreate
+Create empty files only.  \fBfilesize\fR still needs to be specified so that fio
+will run and grab latency results, but no IO will actually be done on the files.
 .SS "I/O engine specific parameters"
 In addition, there are some parameters which are only valid when a specific
 \fBioengine\fR is in use. These are used identically to normal parameters,