Re: [PATCH RFC v2 07/12] schema: Add new domain elements to support multiple throttle filters

From: Chun Feng Wu <wucf(a)linux.ibm.com&gt; * Add new elements '<throttlegroups>' and '<throttlefilters>' * <ThrottleGroups> contains <ThrottleGroup> defintions * <ThrottleFilters> can include multiple throttlegroup references to form filter chain in qemu * Chained throttle filters feature in qemu is described at https://github.com/qemu/qemu/blob/master/docs/throttle.txt Signed-off-by: Chun Feng Wu <wucf(a)linux.ibm.com&gt; ---

docs/formatdomain.rst | 48 +++++++++ src/conf/schemas/domaincommon.rng | 164 +++++++++++++++++++++++++++++- 2 files changed, 211 insertions(+), 1 deletion(-) diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index e2f66b982c..ee9ee8b10c 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -1957,6 +1957,34 @@ advertisements to the guest OS. (NB: Only qemu driver support) the guest OS itself can choose to circumvent the unavailability of the sleep states (e.g. S4 by turning off completely). +Throttle Group Management +-------------------------

+ +:since:`Since 10.3.0` it is possible to create multiple named throttle groups +and then reference them within ``throttlefilters`` to form filter chain in QEMU for +specific disk. The limits(throttlegroups) are shared within domain, hence the same group

+can be referenced by different filters. + +:: + + <domain> + ... + <throttlegroups> + <throttlegroup> + <group_name>limit0</group_name> + <total_bytes_sec>10000000</total_bytes_sec> + <read_iops_sec>400000</read_iops_sec> + <write_iops_sec>100000</write_iops_sec> + </throttlegroup> + </throttlegroups> + ... + </domain> + +All throttlegroups are listed within the ``throttlegroups`` element

+ +``throttlegroup`` + It has the same sub-elements as ``iotune`` (See `Hard drives, floppy disks, CDROMs`_), + The difference is that <group_name> is required.

Hypervisor features ------------------- @@ -2704,6 +2732,15 @@ paravirtualized driver is specified via the ``disk`` element. <source dev='/dev/vhost-vdpa-0' /> <target dev='vdg' bus='virtio'/> </disk> + <disk type='file' device='disk'> + <driver name='qemu' type='qcow2' /> + <source file='/var/lib/libvirt/images/disk.qcow2'/> + <target dev='vdh' bus='virtio'/> + <throttlefilters> + <throttlefilter group='limit2'/> + <throttlefilter group='limit012'/> + </throttlefilters> + </disk> </devices> ... @@ -3185,6 +3222,17 @@ paravirtualized driver is specified via the ``disk`` element. :since:`since after 0.4.4`; "sata" attribute value :since:`since 0.9.7`; "removable" attribute value :since:`since 1.1.3`; "rotation_rate" attribute value :since:`since 7.3.0` +``throttlefilters`` + The optional ``throttlefilters`` element provides the ability to provide additional + per-device throttle chain :since:`Since 10.3.0` + For example, if we have four different disks and we want to limit I/O for each one + and we also want to limit combined I/O of all four disks, we can leverage + ``throttlefilters`` to achieve this goal by setting two ``throttlefilter`` for + each disk: disk's own filter and combined filter. ``throttlefilters`` and ``iotune`` + should be used exclusively.

+ + ``throttlefilter`` + The optional ``throttlefilter`` element is to reference defined throttle group. ``iotune`` The optional ``iotune`` element provides the ability to provide additional per-device I/O tuning, with values that can vary for each device (contrast

@@ -6637,6 +6641,164 @@ </interleave> </element> </define> + <!-- + throttlegroup is similar to <iotune>, however, group_name is required, which is different from <iotune> + --> + <define name="throttlegroup"> + <element name="throttlegroup"> + <interleave> + <!-- required --> + <element name="group_name"> + <text/> + </element> + <choice> + <element name="total_bytes_sec"> + <data type="unsignedLong"/> + </element>

+ <group> + <interleave> + <optional> + <element name="read_bytes_sec"> + <data type="unsignedLong"/> + </element>