Re: [PATCH RFC v3 02/16] schema: Add new domain elements to support multiple throttle filters

On Wed, Jun 12, 2024 at 03:02:10 -0700, wucf(a)linux.ibm.com wrote: > From: Chun Feng Wu <wucf(a)linux.ibm.com&gt; > > * Add new elements '<throttlefilters>' > * <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 | 22 ++++++++++++++++++++++ > src/conf/schemas/domaincommon.rng | 19 ++++++++++++++++++- > 2 files changed, 40 insertions(+), 1 deletion(-) > > diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst > index b7e1f9cc83..0fa8f1267c 100644 > --- a/docs/formatdomain.rst > +++ b/docs/formatdomain.rst > @@ -2736,6 +2736,15 @@ 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> > ... > > @@ -3217,6 +3226,19 @@ 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 10.5.0` > + 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(e.g. limit2) and combined filter(e.g. limit012). > + The nodes in qemu shape a chain like libvirt-4-filter(node name of "limit012") -> > + libvirt-3-filter(node name of "limit2") -> libvirt-2-format -> libvirt-1-storage. > + ``throttlefilters`` and ``iotune`` should be used exclusively. Node names are a qemu driver internal implementation detail and thus must not be noted in documentation.