Missed FIO_UNIDIR io ops flags on net engine

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index 5156adbe1e39c6ae738392e04467d155ee2abe57..3bda021d17c9090929d4276161b346242a0f27c4 100644 (file)
--- 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).
 
@@ -464,10 +469,16 @@ 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
+               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
                jobs, and you want to delay starting some jobs to a certain
@@ -686,9 +697,10 @@ E          Thread exited, not reaped by main thread yet.
 _              Thread reaped.
 
 The other values are fairly self explanatory - number of threads
-currently running and doing io, rate of io since last check, and the estimated
-completion percentage and time for the running group. It's impossible to
-estimate runtime of the following groups (if any).
+currently running and doing io, rate of io since last check (read speed
+listed first, then write speed), and the estimated completion percentage
+and time for the running group. It's impossible to estimate runtime of
+the following groups (if any).
 
 When fio is done (or interrupted by ctrl-c), it will show the data for
 each thread, group of threads, and disks in that order. For each data
@@ -715,7 +727,10 @@ 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,