Dynamic extension of cache coherence snoop filter entry

One or more physically manufactured computer-readable storage media, encoding computer-executable instructions for executing on a computer system a computer process, the computer process comprising:

• generating a base snoop filter (SFT) entry for a coherence granule (cogran) in agent cache, the base SFT entry comprising a tracking_information field configured to track a plurality of agent IDs, each agent ID identifying an agent that holds a copy of the cogran;
• determining a number of agents that hold the copy of the cogran;
• comparing the and number of agents that store the copy of the cogran with number of the plurality of agent IDs tracked in the tracking_information field of the base SFT entry;
• and
• in response to determining that the number of agents that hold the copy of the cogran is greater than the number of the plurality of agent IDs tracked in the tracking_information field of the base SFT entry, selecting a second SFT entry as an extra SFT entry, wherein the extra SFT entry is configured to store a portion of tracking vector wherein each bit of the tracking vector indicates cache validity state of the cogran for a related agent.

A system comprising:

• memory;
• one or more processor units;
• and
• a cache coherence system stored in the memory and executable by the one or more processor units, the cache coherence system encoding computer-executable instructions on the memory for executing on the one or more processor units a computer process, the computer process comprising:
• generating a base snoop filter (SFT) entry for a coherence granule (cogran) in agent cache, the base SFT entry comprising a tracking_information field configured to track a plurality of agent IDs, each agent ID identifying an agent that holds a copy of the cogran;
• determining a number of agents that hold the copy of the cogran;
• comparing the and number of agents that store the copy of the cogran with number of the plurality of agent IDs tracked in the tracking_information field of the base SFT entry;
• and
• in response to determining that the number of agents that hold the copy of the cogran is greater than the number of the plurality of agent IDs tracked in the tracking_information field of the base SFT entry, selecting a second SFT entry as an extra SFT entry, wherein the extra SFT entry is configured to store a portion of tracking vector wherein each bit of the tracking vector indicates cache validity state of the cogran for a related agent.