Use offset VFD start value for storage VM

Author: fwsGonzo

lib/tinykvm/linux/fds.hpp

@@ -43,6 +43,15 @@ namespace tinykvm
 		~FileDescriptors();
 		void reset_to(const FileDescriptors& other);
 
+		/// @brief Set a new starting virtual file descriptor. This is useful
+		/// when there exists a remote VM with its own set of virtual file
+		/// descriptors, and we want to avoid "collisions". FDs can't be
+		/// shared between remote VMs, but it's useful to distinguish them.
+		/// @param vfd_start The new starting virtual file descriptor.
+		void set_vfd_start(int vfd_start) noexcept {
+			m_next_fd = vfd_start;
+		}
+
 		/// @brief Add a file descriptor to the list of managed FDs.
 		/// @param fd The real file descriptor.
 		/// @param is_socket True if the file descriptor is a socket.

src/storage.cpp

@@ -114,6 +114,7 @@ int main(int argc, char** argv)
 	storage_vm.set_verbose_system_calls(getenv("VERBOSE") != nullptr);
 	storage_vm.set_verbose_mmap_syscalls(getenv("VERBOSE") != nullptr);
 	storage_vm.set_verbose_thread_syscalls(getenv("VERBOSE") != nullptr);
+	storage_vm.fds().set_vfd_start(65536); // Avoid "collisions" with master VM
 	storage_vm.fds().set_open_readable_callback(
 		[] (std::string&) -> bool {
 		return true;
@@ -183,7 +184,7 @@ int main(int argc, char** argv)
 	}
 	auto call_overhead = timed_action([&] {
 		for (int i = 0; i < 100; i++)
-			vm.timed_vmcall(do_it->second, 5.0f, 21);
+			vm.vmcall(do_it->second, 5.0f, 21);
 	}) / 100.0;
 	printf("Call overhead: %.2fus\n", call_overhead * 1e6);