METHOD AND APPARATUS FOR
PRIORITIZING AND ROUTING COMMANDS
FROM A COMMAND SOURCE TO A
 Inventors: Donald Lee Freerksen; Peder James Paulson, both of Rochester, Minn.
 Assignee: International Business Machines Corporation, Armonk, N.Y.
[ * ] Notice: This patent is subject to a terminal disclaimer.
 Appl. No.: 08/761,380
 Filed: Dec. 9, 1996
 Int. CI. G06F 13/14
 U.S. CI 711/118
 Field of Search 711/118, 140
 References Cited
U.S. PATENT DOCUMENTS
5,793,977 8/1998 Schmidt 395/200.54
Israel, Paul et al, 1995 Electronic Engineering Times (Jun. 19), pp. 78-80, "Chip Set Aims to Speed Secondary Cache—Parallelism Enhances Level 2 Cache Runs". Jouppi, Norman P., 17th Annual International Symposium on Computer Architecture (May 28-31, 1990) pp. 364-373, "Improving Direct-Mapped Cache Performance by the Addition of a Small Fully-Associative Cache and Prefetch Buffers".
A method and apparatus for prioritizing and routing commands from a command source to a command sink. The command directory receives and stores a command from at least one command source. The data buffer stores the data associated with the command in the allocated portion of the data buffer. Based on status information also stored by the command directory with respect to each command, routing logic in the command directory, corresponding to each command sink, identifies which commands stored in the command buffer to route to the command sink, and routes the identified commands to the command sink. The routing logic also determines a priority of the identified commands and routes the identified commands in order of priority.
16 Claims, 12 Drawing Sheets