@@ -1004,3 +1004,113 @@ some additional tasks, hooking io requests.
.. option:: prealloc-size
How much to preallocate (in bytes), default 128M.
+
+.. program:: filter-drivers
+.. option:: throttle
+
+ The throttle filter driver rate limits I/O requests so that the given IOPS
+ and bandwidth values are not exceeded. Limits are specified using the
+ following syntax::
+
+ --object '{"driver":"throttle-group","id":"tg0","limits":{"iops-total":2048,"bps-total":10485760}}'
+
+ The following throttle group limits are available:
+
+ .. program:: throttle-group
+ .. option:: iops-total
+
+ Limit total I/O operations per second.
+
+ .. option:: iops-total-max
+
+ I/O operations burst.
+
+ .. option:: iops-total-max-length
+
+ Length of the ``iops-total-max`` burst period, in seconds. It must only be
+ set if ``iops-total-max`` is set as well.
+
+ .. option:: iops-read
+
+ Limit read operations per second.
+
+ .. option:: iops-read-max
+
+ I/O operations read burst.
+
+ .. option:: iops-read-max-length
+
+ Length of the ``iops-read-max`` burst period, in seconds. It must only be
+ set if ``iops-read-max`` is set as well.
+
+ .. option:: iops-write
+
+ Limit write operations per second.
+
+ .. option:: iops-write-max
+
+ I/O operations write burst.
+
+ .. option:: iops-write-max-length
+
+ Length of the ``iops-write-max`` burst period, in seconds. It must only be
+ set if ``iops-write-max`` is set as well.
+
+ .. option:: bps-total
+
+ Limit total bytes per second.
+
+ .. option:: bps-total-max
+
+ Total bytes burst.
+
+ .. option:: bps-total-max-length
+
+ Length of the ``bps-total-max`` burst period, in seconds. It must only be
+ set if ``bps-total-max`` is set as well.
+
+ .. option:: bps-read
+
+ Limit read bytes per second.
+
+ .. option:: bps-read-max
+
+ Total bytes read burst.
+
+ .. option:: bps-read-max-length
+
+ Length of the ``bps-read-max`` burst period, in seconds. It must only be
+ set if ``bps-read-max`` is set as well.
+
+ .. option:: bps-write
+
+ Limit write bytes per second.
+
+ .. option:: bps-write-max
+
+ Total bytes write burst.
+
+ .. option:: bps-write-max-length
+
+ Length of the ``bps-write-max`` burst period, in seconds. It must only be
+ set if ``bps-write-max`` is set as well.
+
+ .. option:: iops-size
+
+ IOPS are counted as a multiple of this value, in bytes. For example, a 16
+ KB read request is counted as 4 IOPS when ``iops-size`` is 4 KB.
+
+ Throttle groups are defined separately from throttle blockdevs so they can be
+ shared by multiple blockdevs.
+
+ Note that the location of the throttle blockdev in the graph is significant.
+ Usually it will be one of the topmost nodes so that guest I/O requests are
+ throttled. When the throttle blockdev is located below a format driver it may
+ see a different I/O pattern due to image format metadata I/O.
+
+ Supported runtime options:
+
+ .. program:: throttle
+ .. option:: throttle-group
+
+ The id of the throttle group object that defines the I/O limits.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- docs/system/qemu-block-drivers.rst.inc | 110 +++++++++++++++++++++++++ 1 file changed, 110 insertions(+)