Re: [libvirt] [PATCH 1/3] add percentage limit parse and define support for RAM filesystems

On 12/05/2013 04:56 AM, Daniel P. Berrange wrote: >>>>> >>>>> This patch enables percentage limit for ram filesystem >>>>> >>>>> <filesystem type='ram'> >>>>> <source usage='10%'/> >>>>> <target dir='/mnt'/> >>>>> </filesystem> >>>>> > > I just don't see this as a compelling feature. I think it is more important > to have a single canonical representation of memory allocation. User > convenience is something for higher level tools to worry about. But do higher level tools already have a way to query libvirt what the current host's available ram is, in order to determine percentages itself? We can't really migrate online LXC guests, but for an offline guest setup, copying XML from one host with small memory to another host with large memory, and still having the guest have a fixed percentage of the host resources (more memory assigned to the guest on the larger host), seems like a reasonable desire; to achieve that, the management tool needs to be able to either request percentages (no change to the guest xml being copied) or know the host resource limits (and rewrite the xml rather than merely copy it).