On Tue, 11 Nov 2008 20:48:16 +0200 Avi Kivity <[EMAIL PROTECTED]> wrote:
> Andrew Morton wrote: > > The whole approach seems wrong to me. The kernel lost track of these > > pages and then we run around post-facto trying to fix that up again. > > Please explain (for the changelog) why the kernel cannot get this right > > via the usual sharing, refcounting and COWing approaches. > > > > For kvm, the kernel never knew those pages were shared. They are loaded > from independent (possibly compressed and encrypted) disk images. These > images are different; but some pages happen to be the same because they > came from the same installation media. What userspace-only changes could fix this? Identify the common data, write it to a flat file and mmap it, something like that? > For OpenVZ the situation is less clear, but if you allow users to > independently upgrade their chroots you will eventually arrive at the > same scenario (unless of course you apply the same merging strategy at > the filesystem level). hm. There has been the occasional discussion about idenfifying all-zeroes pages and scavenging them, repointing them at the zero page. Could this infrastructure be used for that? (And how much would we gain from it?) [I'm looking for reasons why this is more than a muck-up-the-vm-for-kvm thing here ;) ] -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
