[libvirt] [PATCH] libvirt/hooks: Static and dynamic hugepage hooks

[Alex Williamson]

On Wed, 2015-06-24 at 12:57 -0600, Alex Williamson wrote:
> This patch provides scripts for hugepage allocation, as well as a bit
> of infrastructure and common hook config file that I hope may some day
> be enabled by default in libvirt.  For now, we place the files in
> /usr/share and ask users to install the config file and copy or link
> the scripts, more like "contrib" scripts for now.
> 
> Two methods of hugepage allocation are provided, static and dynamic.
> The static mechanism allocates pages at libvirt daemon startup and
> releases them at shutdown.  It allows full size, locality, and policy
> configuration.  For instance, if I want to allocate a set of 2M pages
> exclusively on host NUMA node 1, it can do that, along with plenty
> more.  This is especially useful for 1G hugepages on x86, since they
> can now be allocated dynamically, but become impractical to allocate
> due to memory fragmentation as the host runs.  Systems dedicated to
> hosting VMs are also likely to prefer static allocation.  Static
> allocation requires explicit XML entries in the hook config file to
> be activated.
> 
> The dynamic method allocates hugepages only around the instantiation
> of the VM.  This is enabled by adding an entry for the domain in the
> config file and configuring the domain normally for hugepages.  The
> dynamic hugepage script is activated via the QEMU domain prepare
> hook, reads the domain XML and allocates hugepages as necessary.  On
> domain shutdown, hugepages are freed via the release hook.  This
> model is more appropriate for systems that are not dedicated VM
> hosts and guests that use hugepage sizes and quantities are are
> likely to be dynamically allocated as the VM is started.
> 
> In addition to the documentation provided within each script, a README
> file is provided with overal instructions and summaries of the
> individual scripts.
> 
> Signed-off-by: Alex Williamson <alex.williamson at redhat.com>
> ---


I'm going to self-nak this because I think I've misinterpreted the
nodeset on hugepages/page to be host node rather than guest node.  I'll
need to re-jig the algorithm.  Thanks,

Alex