On 2019/11/30 上午5:34, Peter Xu wrote:
Branch is here:https://github.com/xzpeter/linux/tree/kvm-dirty-ring Overview ============ This is a continued work from Lei Cao<lei.cao@xxxxxxxxxxx> and Paolo on the KVM dirty ring interface. To make it simple, I'll still start with version 1 as RFC. The new dirty ring interface is another way to collect dirty pages for the virtual machine, but it is different from the existing dirty logging interface in a few ways, majorly: - Data format: The dirty data was in a ring format rather than a bitmap format, so the size of data to sync for dirty logging does not depend on the size of guest memory any more, but speed of dirtying. Also, the dirty ring is per-vcpu (currently plus another per-vm ring, so total ring number is N+1), while the dirty bitmap is per-vm. - Data copy: The sync of dirty pages does not need data copy any more, but instead the ring is shared between the userspace and kernel by page sharings (mmap() on either the vm fd or vcpu fd) - Interface: Instead of using the old KVM_GET_DIRTY_LOG, KVM_CLEAR_DIRTY_LOG interfaces, the new ring uses a new interface called KVM_RESET_DIRTY_RINGS when we want to reset the collected dirty pages to protected mode again (works like KVM_CLEAR_DIRTY_LOG, but ring based) And more.
Looks really interesting, I wonder if we can make this as a library then we can reuse it for vhost.
Thanks
