partial use of copy on write segments in a computer - with virtual machines and virtual memory

摘要

Copy-on-write segment sharing is accommodated in a virtual memory virtual machine data processing system in which a Virtual Resource Manager establishes virtual machines which execute at least one UNIX type operating system which includes SHMAT type System Calls to permit a file to be concurrently shared by more than one user. An improved System Call is provided to create a copy-on-write type file that can be shared. A mapped file type segment is established and provides two special fields in the map node data structure that function to control the concurrent use of the copy-on-write segment by multiple users.