On Thu, Feb 23, 2012 at 04:42:54PM +0000, Stefan Hajnoczi wrote: > On Thu, Feb 23, 2012 at 3:40 PM, Peter Lieven <pl@xxxxxxx> 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 :). > That was attempted. It is called "page hinting", but AFAIK due to complex locking issue attempt was abandoned. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
