On Wed, Jan 10, 2024 at 15:54:18 +0100, Michal Prívozník wrote: > On 1/10/24 12:59, Peter Krempa wrote: > > On Fri, Jan 05, 2024 at 13:33:32 +0100, Michal Privoznik wrote: > >> Introduced in v8.2.0-rc0~74^2~2, QEMU now allows setting > >> .dynamic-memslots attribute for virtio-mem-pci devices. When > >> turned on, it allows memory exposed to guest to be split into > >> multiple memslots and thus smaller memory footprint (see the > >> original commit for detailed explanation). > >> > >> Therefore, introduce new <target/> attribute which will control > >> that QEMU knob. > >> > >> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> > >> --- > >> docs/formatdomain.rst | 6 ++++++ > >> src/conf/domain_conf.c | 18 +++++++++++++++++- > >> src/conf/domain_conf.h | 1 + > >> src/conf/schemas/domaincommon.rng | 5 +++++ > >> .../memory-hotplug-virtio-mem.xml | 2 +- > >> 5 files changed, 30 insertions(+), 2 deletions(-) > >> > >> diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst > >> index 96e03a3807..57974de9f4 100644 > >> --- a/docs/formatdomain.rst > >> +++ b/docs/formatdomain.rst > >> @@ -8395,6 +8395,12 @@ Example: usage of the memory devices > >> The ``node`` subelement configures the guest NUMA node to attach the memory > >> to. The element shall be used only if the guest has NUMA nodes configured. > >> > >> + For ``virtio-mem`` optional attribute ``dynamicMemslots`` can be specified > >> + (accepted values "yes"/"no") which allows hypervisor to spread memory into > >> + multiple memory slots (allocate them dynamically based on the amount of > >> + memory exposed to the guest), resulting in smaller memory footprint. > >> + :since:`Since 10.0.0 and QEMU 8.2.0` > >> + > > > > Except for the docs here, which are insufficient as outlined in the > > other subthread, the code looks good, so for the code: > > How about this: > > For ``virtio-mem`` optional attribute ``dynamicMemslots`` can be specified > (accepted values "yes"/"no") which allows hypervisor to spread memory into > multiple memory slots (allocate them dynamically based on the amount of > memory exposed to the guest), resulting in smaller memory footprint. But be > aware this may affect vhost-user devices. When enabled, older vhost-user I'd add: 'vhost-user devices (such as virtiofsd)'. Optionally you can add more, but virtiofsd is the one users can configure without being aware of it.a also perhaps 'vhost-user device implementations' for the next sentence. > devices may refuse to initialize resulting in failed domain startup or > device hotplug (set this to "no" then). On the other hand, modern vhost-user IMO the stuff in the parentheses can be dropped. > devices, or when no vhost-user devices are present (nor they will be > hotplugged), this leads to smaller memory footprint (set this to "yes" the memory footprint note is redundant from the first sentence. How about: When only modern vhost-user based devices will be used or when no vhost-user devices are expected to be used it's beneficial to enable this feature. > then). The current default is hypervisor dependant (for QEMU is "no"). If > the default changes and you are having difficulties with vhost-user devices, > try toggling this to "no". :since:`Since 10.1.0 and QEMU 8.2.0` > > > > > > Reviewed-by: Peter Krempa <pkrempa@xxxxxxxxxx> > > > > Thank you! > > Michal > _______________________________________________ Devel mailing list -- devel@xxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxx
