Fix rate option with iodepth > 1

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index bc23052d61e568434b23488c150e525d0ee48407..45a96bb1618182c0251fb8a77a4bdfd1ab6e460b 100644 (file)
--- 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
 
 
 $ 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 "${VARNAME}" as part of an option value (in other
 words, on the right of the `='), will be expanded to the value of the
 fio also supports environment variable expansion in job files. Any
 substring of the form "${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.
 
 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
 -------------------------------
 
 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
 
                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
 
 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.
 
                        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
                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
 
 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.
                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
 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.
 
                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
 ---------------------------
 
 6.0 Interpreting the output
 ---------------------------