Re: KVM architecture docs

Zhao Forrest
2008-03-05T06:51:55Z

> >
> > Normally swapping mechanism choose the Least Recently Used(LRU) pages
> > of a process to be swapped out. When KVM uses MMU notifier in linux
> > kernel to implement swapping for VM, could KVM choose LRU pages of a
> > VM to swap out? If so, could you give a brief description about how
> > this is implemented?
> >
>
> The Linux memory manager approximates LRU by scanning pages for the
> accessed bit, which is set in the pte by the processor when a page is
> accessed through that pte. mmu notifiers provide a callback for the
> check, so that kvm can check the accessed bit on the shadow ptes.

Linux kernel maintains a reverse mapping from a page frame to all page tables
pointing to this page frame. Does KVM need to maintain a similar reverse mapping
from a page frame to all shadow page tables pointing to this page frame?
I should have read the code to find the answer. But it's appreciated
if you could give
a quick answer :)

Thanks,
Forrest