+xbt::signal<void(Io const&, Actor const&)> Io::on_start;
+xbt::signal<void(Io const&, Actor const&)> Io::on_completion;
+
+Io::Io(sg_disk_t disk, sg_size_t size, OpType type) : disk_(disk), size_(size), type_(type)
+{
+ Activity::set_remaining(size_);
+ pimpl_ = kernel::activity::IoImplPtr(new kernel::activity::IoImpl());
+}