* Avi Kivity <avi@xxxxxxxxxx> [2010-03-15 11:27:56]: > >>>The knobs are for > >>> > >>>1. Selective enablement > >>>2. Selective control of the % of unmapped pages > >>An alternative path is to enable KSM for page cache. Then we have > >>direct read-only guest access to host page cache, without any guest > >>modifications required. That will be pretty difficult to achieve > >>though - will need a readonly bit in the page cache radix tree, and > >>teach all paths to honour it. > >> > >Yes, it is, I've taken a quick look. I am not sure if de-duplication > >would be the best approach, may be dropping the page in the page cache > >might be a good first step. Data consistency would be much easier to > >maintain that way, as long as the guest is not writing frequently to > >that page, we don't need the page cache in the host. > > Trimming the host page cache should happen automatically under > pressure. Since the page is cached by the guest, it won't be > re-read, so the host page is not frequently used and then dropped. > Yes, agreed, but dropping is easier than tagging cache as read-only and getting everybody to understand read-only cached pages. -- Three Cheers, Balbir -- 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
