On 11/29/2011 10:03 PM, Avi Kivity wrote: > On 11/29/2011 02:01 PM, Avi Kivity wrote: >> On 11/29/2011 01:56 PM, Xiao Guangrong wrote: >>> On 11/29/2011 07:20 PM, Avi Kivity wrote: >>> >>> >>>> We used to have a bitmap in a shadow page with a bit set for every slot >>>> pointed to by the page. If we extend this to non-leaf pages (so, when >>>> we set a bit, we propagate it through its parent_ptes list), then we do >>>> the following on write fault: >>>> >>> >>> >>> Thanks for the detail. >>> >>> Um, propagating slot bit to parent ptes is little slow, especially, it >>> is the overload for no Xwindow guests which is dirty logged only in the >>> migration(i guess most linux guests are running on this mode and migration >>> is not frequent). No? >> >> You need to propagate very infrequently. The first pte added to a page >> will need to propagate, but the second (if from the same slot, which is >> likely) will already have the bit set in the page, so we're assured it's >> set in all its parents. > > btw, if you plan to work on this, let's agree on pseudocode/data > structures first to minimize churn. I'll also want this documented in > mmu.txt. Of course we can still end up with something different than > planned, but let's at least try to think of the issues in advance. > Yeap, this work is interesting, i will keep researching it. ;) -- 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
