openstack/devstack
Code Issues Proposed changes

Use Nehalem CPU model by default

Browse Source 
CentOS/RHEL 9 are being compiled for the x86_64-v2 architecture which is
newer than the qemu default of qemu64. This means that for devstack to
boot these instances we need a newer CPU model. Nehalem is apparently
the oldest model that works for x86_64-v2 and is expected to work on
Intel and AMD cpus with kvm or qemu. Switch devstack to this model by
default.

Note that we cannot use host-passthrough or host-model because we want
to support live migration between devstack deployed nova-compute
instances and even within the CI instances that we get the host CPUs can
differ.

Also, we should run this change against as many clouds as possible to
ensure that the newer model works across all of our clouds. There is
some fear that the virtual CPUs presented to us in some clouds may not
be able to run these newer CPU models.

Change-Id: Ibd6e11b59f3c8655bc60ace7383a08458b2177f2
This commit is contained in:
Clark Boylan 2021-10-21 08:15:12 -07:00
parent 6923f7b5e6
commit e06d954229
3 changed files with 7 additions and 2 deletions
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3
lib/nova
View File

@ -260,7 +260,8 @@ function configure_nova {
if [ ! -e /dev/kvm ]; then
echo "WARNING: Switching to QEMU"
LIBVIRT_TYPE=qemu
LIBVIRT_CPU_MODE=none
LIBVIRT_CPU_MODE=custom
LIBVIRT_CPU_MODEL=Nehalem
if which selinuxenabled >/dev/null 2>&1 && selinuxenabled; then
# https://bugzilla.redhat.com/show_bug.cgi?id=753589
sudo setsebool virt_use_execmem on

3
lib/nova_plugins/hypervisor-libvirt
View File

@ -40,6 +40,9 @@ function configure_nova_hypervisor {
configure_libvirt
iniset $NOVA_CONF libvirt virt_type "$LIBVIRT_TYPE"
iniset $NOVA_CONF libvirt cpu_mode "$LIBVIRT_CPU_MODE"
if [ "$LIBVIRT_CPU_MODE" == "custom" ] ; then
iniset $NOVA_CONF libvirt cpu_model "$LIBVIRT_CPU_MODEL"
fi
# Do not enable USB tablet input devices to avoid QEMU CPU overhead.
iniset $NOVA_CONF DEFAULT pointer_model "ps2mouse"
iniset $NOVA_CONF libvirt live_migration_uri "qemu+ssh://$STACK_USER@%s/system"

3
stackrc
View File

@ -623,7 +623,8 @@ VIRT_DRIVER=${VIRT_DRIVER:-$DEFAULT_VIRT_DRIVER}
case "$VIRT_DRIVER" in
ironic|libvirt)
LIBVIRT_TYPE=${LIBVIRT_TYPE:-kvm}
LIBVIRT_CPU_MODE=${LIBVIRT_CPU_MODE:-none}
LIBVIRT_CPU_MODE=${LIBVIRT_CPU_MODE:-custom}
LIBVIRT_CPU_MODEL=${LIBVIRT_CPU_MODEL:-Nehalem}
if [[ "$os_VENDOR" =~ (Debian|Ubuntu) ]]; then
# The groups change with newer libvirt. Older Ubuntu used
# 'libvirtd', but now uses libvirt like Debian. Do a quick check