On Thu, Feb 23, 2012 at 3:40 PM, Peter Lieven <p...@dlh.net> 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
