On 03/03/11 00:41, Ross Walker wrote: [...snip...] > > This works with Xen or KVM, though the management and > compartmentalization of Xen helps. > > Does CentOS support the shared memory pages, memory dedup, in Xen? That > would allow for a lot more Linux VMs. I don't think the KSM support has been backported to the RHEL5/CentOS5 kernels. I might remember wrong though. _If_ KSM is available on the 2.6.18 based kernels, it should definitely work for KVM on RHEL5/CentOS5. However, I doubt it has been backported to the Xen dom0 kernels. If I've understood it correctly, the Xen hypervisor is its own microkernel and dom0 is kind of a virtual guest with more privileges than domUs, to be able to administer and control the guests. IIRC, this micro kernel got its own scheduler and memory management too. While with KVM, the host kernel (which loads the kvm.ko module) is the hypervisor, and all the virtual guests are qemu-kvm user space processes. And KSM will merge "same pages" for user space processes, no matter if it is KVM guests or other applications. kind regards, David Sommerseth