Open Stack

Hello,

We are working on SR-IOV & DPDK tripleo integration. In which, setting
the kernel args for huge pages, iommu and cpu isolation is required.
Earlier we were working on setting of kernel args via IPA [1], reasons
being:
1. IPA is installing the boot loader on the overcloud node
2. Ironic knows the hardware spec, using which, we can target specific
args to nodes via introspection rules

As the proposal is to change the image owned file '/etc/default/grub',
it has been suggested by ironic team to use the instance user data to
set the kernel args [2][3], instead of IPA. In the suggested approach,
we are planning to update the file /etc/default/grub, update
/etc/grub2.cfg and then issue a reboot. Reboot is mandatory because,
os-net-config will configure the DPDK bridges and ports by binding the
DPDK driver, which requires kernel args should be set for iommu and
huge pages.

As discussed on the IRC tripleo meeting, we need to ensure that the
user data with update of kernel args, does not overlap with any other
puppet configurations. Please let us know if you have any comments on
this approach.

Regards,
Saravanan KR

[1] https://review.openstack.org/#/c/331564/
[2] http://docs.openstack.org/developer/ironic/deploy/install-guide.html#appending-kernel-parameters-to-boot-instances
[3] http://docs.openstack.org/developer/tripleo-docs/advanced_deployment/extra_config.html#firstboot-extra-configuration