On 03/13/2012 11:20 AM, Takuya Yoshikawa wrote: > Avi Kivity <avi@xxxxxxxxxx> wrote: > > > It occurs to me that we should write-protect huge page tables, since it > > makes write protection much faster (we make up for this later at write > > fault time, but that might not occur, and even if it does we reduce > > guest jitter). In fact I once proposed a more involved variant, called > > Do you mean protecting huge page tables when we start logging and dropping > them, one by one, at the time of write fault? Yes. Even more generally, protecting PML4Es, then at fault time un-protecting the faulting PML4E and write-protecting all underlying PDPEs except the one for the faulting address, and similarly for PDEs and PTEs. > If so, we do not need to change get_dirty_log() implementation. > Changing kvm_mmu_remove_write_access() and fault handler seems to be enough. > > > O(1) write protection, in which we write-protect the topmost page table > > only and only un-write-protect the paths that fault. > > > That can be done later however and shouldn't affect this patchset. > > I have some additional patches to optimize rmap handling which seems to > improve get_dirty_log() about 10% in the worst case. Great, looking forward. > After that, I want to take some time to prepare for further developments > because my current test tools are not enough now. > -- error compiling committee.c: too many arguments to function -- 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
