X-Git-Url: https://git.kernel.dk/?p=fio.git;a=blobdiff_plain;f=HOWTO;h=e7142c57b03df0e6f500b35ad95cf712d4c20617;hp=a1513e1259f7cc3001fb185a662150a9527dba34;hb=83c8b093f35169c8e4a38148320881a7ca7b8613;hpb=645943c03a60a61fc2494480cde1f051f8a14111 diff --git a/HOWTO b/HOWTO index a1513e12..e7142c57 100644 --- a/HOWTO +++ b/HOWTO @@ -218,7 +218,7 @@ Command line options Set the maximum number of threads/processes to support to `nr`. NOTE: On Linux, it may be necessary to increase the shared-memory - limit ('/proc/sys/kernel/shmmax') if fio runs into errors while + limit (:file:`/proc/sys/kernel/shmmax`) if fio runs into errors while creating jobs. .. option:: --server=args @@ -233,7 +233,7 @@ Command line options .. option:: --client=hostname Instead of running the jobs locally, send and run them on the given `hostname` - or set of `hostname`s. See `Client/Server`_ section. + or set of `hostname`\s. See `Client/Server`_ section. .. option:: --remote-config=file @@ -1128,13 +1128,20 @@ I/O type .. option:: offset=int Start I/O at the provided offset in the file, given as either a fixed size in - bytes or a percentage. If a percentage is given, the next ``blockalign``-ed - offset will be used. Data before the given offset will not be touched. This + bytes or a percentage. If a percentage is given, the generated offset will be + aligned to the minimum ``blocksize`` or to the value of ``offset_align`` if + provided. Data before the given offset will not be touched. This effectively caps the file size at `real_size - offset`. Can be combined with :option:`size` to constrain the start and end range of the I/O workload. A percentage can be specified by a number between 1 and 100 followed by '%', for example, ``offset=20%`` to specify 20%. +.. option:: offset_align=int + + If set to non-zero value, the byte offset generated by a percentage ``offset`` + is aligned upwards to this value. Defaults to 0 meaning that a percentage + offset is aligned to the minimum block size. + .. option:: offset_increment=int If this is provided, then the real offset becomes `offset + offset_increment @@ -1715,7 +1722,7 @@ I/O engine Doesn't transfer any data, but burns CPU cycles according to the :option:`cpuload` and :option:`cpuchunks` options. Setting :option:`cpuload`\=85 will cause that job to do nothing but burn 85% - of the CPU. In case of SMP machines, use :option:`numjobs`= + of the CPU. In case of SMP machines, use :option:`numjobs`\= to get desired CPU usage, as the cpuload only loads a single CPU at the desired rate. A job never finishes unless there is at least one non-cpuio job.