公开(公告)号：CA2062910C

公开(公告)日：1998-09-22

申请号：CA2062910

申请日：1992-03-12

Applicant: IBM

Inventor： BAYLOR SANDRA J ,  MCAULIFFE KEVIN P ,  RATHI BHARAT D

IPC: G06F12/08 ,  G06F15/16 ,  G06F15/177

Abstract: A directory-based protocol is provided for maintaining data coherency in a multiprocessing (MP) system having a number of processors with associated write-back caches, a multistage interconnection network (MIN) leading to a shared memory, and a global directory associated with the main memory to keep track of state and control information of cache lines. Upon a request by a requesting cache for a cache line which has been exclusively modified by a source cache, two buffers are situated in the global directory to collectively intercept modified data words of the modified cache line during the write-back to memory. A modified word buffer is used to capture modified words within the modified cache line. Moreover, a line buffer stores an old cache line transferred from the memory, during the write back operation. Finally, the line buffer and the modified word buffer, together, provide the entire modified line to a requesting cache.

公开(公告)号：CA2062910A1

公开(公告)日：1992-11-24

申请号：CA2062910

申请日：1992-03-12

Applicant: IBM

Inventor： BAYLOR SANDRA J ,  MCAULIFFE KEVIN P ,  RATHI BHARAT D

IPC: G06F12/08 ,  G06F15/16 ,  G06F15/177