Fio 1.37

[fio.git] / HOWTO

diff --git a/HOWTO b/HOWTO
index cdd6473b28f3574f7a8eca445715cb3d7156b93e..886515b7aa754527070ee24ab785d66abb5b0b3e 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
@@ -318,6 +324,11 @@ kb_base=int        The base unit for a kilobyte. The defacto base is 2^10, 1024.
 randrepeat=bool        For random IO workloads, seed the generator in a predictable
                way so that results are repeatable across repetitions.
 
+fallocate=bool By default, fio will use fallocate() to advise the system
+               of the size of the file we are going to write. This can be
+               turned off with fallocate=0. May not be available on all
+               supported platforms.
+
 fadvise_hint=bool By default, fio will use fadvise() to advise the kernel
                on what IO patterns it is likely to issue. Sometimes you
                want to test specific IO patterns without telling the
@@ -557,6 +568,8 @@ fsync=int   If writing to a file, issue a sync of the dirty data
 
 fsyncdata=int  Like fsync= but uses fdatasync() to only sync data and not
                metadata blocks.
+               In FreeBSD there is no fdatasync(), this falls back to
+               using fsync()
 
 overwrite=bool If true, writes to a file will always overwrite existing
                data. If the file doesn't already exist, it will be
@@ -988,6 +1001,7 @@ 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 +1011,21 @@ 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=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
 ---------------------------