Y-Invalidate: A New Protocol for Implementing Weak Consistency in DSM Systems

摘要

In this work we propose and implement a new variant of the well-known write invalidate protocol called "Y-invalidate." Whereas the former protocol required that every copy of a page be invalidated every time that page is updated, our variant invalidates a copy of a page at process A only at the next synchroniza- tion point which is relevant to A and or if the copy was modified by the owner's process after the page was copied to A. We thus avoid invalidating copies of pages that were modified but never read after modification, and avoid, of course, the associated overhead. Y-Invalidate is basically a weak-consistency protocol.