Patent ID: 11934307
Assignee: ARM LIMITED
Field: Computer technology (Electrical engineering)
Classification: CPC G | IPC G

Claim 19:
20. The apparatus as claimed in claim 18, wherein:
the presence data takes the form of a vector of presence bits for each set in the lower level snoop filter table;
when coherence data for an address is allocated in an entry of a given set in the lower level snoop filter table, a chosen subset of bits of the address are used to set at least one presence bit in the vector provided for the given set; and
a chosen subset of bits of the identified address are used to identify at least one presence bit in the vector provided for the set in the lower level snoop filter table associated with the identified address, and the snoop control circuitry is arranged to determine that an access to the lower level snoop filter table is not required if any of the at least one identified presence bits is clear.