Add support for blkio cgroups on Linux

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index eb8f453ca309b156d279ce1c7a678cefccb6eb6b..7a7d14ea0816080d794d25f4d899603e2eee57a8 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -203,7 +203,13 @@ $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.
+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
@@ -823,7 +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
@@ -842,13 +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
@@ -983,6 +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
@@ -992,6 +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_root=str        Root of the mounted blkio cgroup file systems. This is a Linux
+               specific IO controller. If your system doesn't have it mounted,
+               you can do so with:
+
+               # mount -t cgroup -o blkio none /cgroup
+
+               The cgroup_root defaults to /cgroup, if mounted elsewhere
+               please specify this option.
+
+cgroup=str     Add job to this control group. If it doesn't exist, it will
+               be created.
+
+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.
 
 6.0 Interpreting the output
 ---------------------------