Add support for blkio cgroups on Linux

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index cdd6473b28f3574f7a8eca445715cb3d7156b93e..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
@@ -988,6 +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
@@ -997,6 +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
 ---------------------------