Re: [Qemu-devel] linux guests and ksm performance

[Stefan Hajnoczi]

On Thu, Feb 23, 2012 at 3:40 PM, Peter Lieven <address@hidden> wrote:
> However, in a virtual machine I have not observed the above slow down to
> that extend
> while the benefit of zero after free in a virtualisation environment is
> obvious:
>
> 1) zero pages can easily be merged by ksm or other technique.
> 2) zero (dup) pages are a lot faster to transfer in case of migration.

The other approach is a memory page "discard" mechanism - which
obviously requires more code changes than zeroing freed pages.

The advantage is that we don't take the brute-force and CPU intensive
approach of zeroing pages.  It would be like a fine-grained ballooning
feature.

I hope someone will follow up saying this has already been done or
prototyped :).

Stefan