Re: [libvirt] libxl: calculating free pages in libvirt

On Thu, 2013-06-06 at 15:53 +0200, Dario Faggioli wrote: > Hi Jim, > > As I told you in Dublin, I'm looking into libvirt a bit, with the main > purpose of implementing the NUMA interface for the libxl driver. > > While at it I noticed that libxlNodeGetFreeMemory() uses the value > contained in phy_info.free_pages to check how many pages of free memory > we have. > > However, starting from (Xen's git) commit bec8f17e, the number of free > pages should be computed like this: > > (phy_info.free_pages - phy_info.outstanding_pages) > > to take the memory claiming mechanism introduced by Oracle properly into > account. This only really matters if libvirt wants to coexist on a host with toolstacks which use claim, otherwise outstanding pages will never be non-zero. I don't know if coexistence is a goal or not.

> For other features added within this last dev cycle, libxl has a > `#define LIBXL_HAVE_<foo>' (e.g., LIBXL_HAVE_DOMAIN_NODEAFFINITY), but I > don't see one for this particular field... Konrad, Ian, am I missing it? I don't think so, we seem to have forgotten. > If no, should we add it? Yes, I think that would be wise.