On 11/18/2010 03:10 PM, Jan Kiszka wrote:
Am 18.11.2010 13:54, Avi Kivity wrote: > On 11/18/2010 07:14 AM, Takuya Yoshikawa wrote: >> This patch introduces the counter to hold the number of dirty bits in >> each >> memslot. We will use this to optimize dirty logging later. >> >> >> @@ -3217,11 +3216,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, >> >> n = kvm_dirty_bitmap_bytes(memslot); >> >> - for (i = 0; !is_dirty&& i< n/sizeof(long); i++) >> - is_dirty = memslot->dirty_bitmap[i]; >> - > > This can already be an improvement. /Me wonders if it wouldn't make sense to expand this optimization to the user space interface as well, i.e. signaling "there are no dirty pages" via some flag instead of writing zeros in a bitmap. Of course, this means supporting both interfaces for a longer period.
An 8MB framebuffer is 2K bits, or 256 bytes wide. Comparing 256 cache hot bytes against zero is not worth a new interface.
Larger memory slots are very unlikely to be always unmodified. -- 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
