zlacker

>>hugodu+(OP)
I really want VM's to integrate 'smarter' with the host.

For example, if I'm running 5 VM's, there is a good chance that many of the pages are identical. Not only do I want those pages to be deduplicated, but I want them to be zero-copy (ie. not deduplicated after-the-fact by some daemon).

To do that, the guest block cache needs to be integrated with the host block-cache, so that whenever some guest application tries to map data from disk, the host notices that another virtual machine has already caused this data to be loaded, so we can just map the same page of already loaded data into the VM that is asking.

>>london+f4
OpenVZ does this. If you have 5 VMs each loading the same library then memory is conserved, as I understand it.

>>shrubb+D9
kvm does the same with KSM.

>>anthk+Rd
Not precisely, in that KSM does it after the fact while OpenVZ has it occur as a consequence of its design, on the loading of the program.

See (OpenVZ) "Containers share dynamic libraries, which greatly saves memory." It's just 1 Linux kernel when you are running OpenVZ containers.

https://docs.openvz.org/openvz_users_guide.webhelp/_openvz_c...

See (KVM/KSM): "KSM enables the kernel to examine two or more already running programs and compare their memory. If any memory regions or pages are identical, KSM reduces multiple identical memory pages to a single page. This page is then marked copy on write."

https://access.redhat.com/documentation/en-us/red_hat_enterp...

In KVM's defense, it supports a much wider range of OSes; OpenVZ only really does different versions of Linux, while KVM can run OpenBSD/FreeBSD/NetBSD/Windows and even OS/2 in addition to Linux.