US 7,617,366 B2
Method and apparatus for filtering snoop requests using mulitiple snoop caches
Matthias A. Blumrich, Ridgefield, Conn. (US); Alan G. Gara, Mount Kisco, N.Y. (US); Mark E. Giampapa, Irvington, N.Y. (US); Martin Ohmacht, Yorktown Heights, N.Y. (US); and Valentina Salapura, Chappaqua, N.Y. (US)
Assigned to International Business Machines Corporation, Armonk, N.Y. (US)
Filed on May 01, 2008, as Appl. No. 12/113,756.
Application 12/113756 is a continuation of application No. 11/093132, filed on Mar. 29, 2005, granted, now 7,386,684.
Prior Publication US 2008/0209128 A1, Aug. 28, 2008
Int. Cl. G06F 13/28 (2006.01); G06F 12/00 (2006.01)
U.S. Cl. 711—146  [711/100; 711/128; 711/154] 20 Claims
OG exemplary drawing
 
1. A cache wrap detection apparatus for detecting when entire contents of a cache memory device associated wit a processor device in a computing environment have been replaced relative to an identified starting state, said cache memory device comprising an N-way set associative cache, said cache wrap detection apparatus comprising:
an interface for monitoring signals asserted by said processor device when performing processor cache updates, said signals including update indicator signals for each cache update occurring, an update indicator signal for each cache update being associated with a particular cache line in a set i, where i ∈{1, . . . , N} within said N-way set-associative cache; and,
for each set i, a cache wrap detection logic means responsive to said update indicator signals for detecting a wrap condition in said set i, and, asserting a set_wrap(i) signal when all lines within that set have been replaced,
a means for receiving each said asserted set_wrap(i) signal and generating a cache wrap detection signal when a cache wrap has occurred for all sets of said N-way set associative cache and all lines of the cache memory device have been replaced relative to said identified starting state,
wherein said monitored signals further comprise a cache way signal indicating a current cache line being replaced in a particular set i, said cache wrap detection logic means comprising:
a register device loaded with data indicating a single cache way that must be updated to complete a set wrap condition in said set i; and,
comparator means for receiving said cache way signals and asserting a signal when a received cache way signal matches the loaded cache way data content of the register device.