Coarse grain coherency

A heterogeneous data processing system comprising:

• a general-purpose processor including a first cache memory and a first coherency module;
• a general-purpose graphics processor including a second cache memory and a second coherency module, wherein the first coherency module and the second coherency module enable heterogeneous coherency between the first cache memory and the second cache memory, the heterogeneous coherency enabled at multiple cache line granularity, wherein data storage for the first cache memory is managed at cache line granularity, coherence for sub-page shared virtual memory allocations cached by the first cache memory and the second cache memory are managed at superline granularity, and the second cache memory is a last level cache shared between the general-purpose processor and the general-purpose graphics processor;
• and
• a first memory module to store a superline directory table, the superline directory table to track ownership for each superline owned by the general-purpose processor and the general-purpose graphics processor, wherein each superline is a sub-page address region that spans multiple cache lines of the first cache memory and the second cache memory.

A non-transitory machine-readable medium storing instructions to perform operations on one or more processors of an agent of a heterogeneous processing system, the operations comprising:

• receiving a request to access a virtual memory address from a process executing on the agent;
• determining if the agent has ownership of a first superline associated with the virtual memory address, the first superline associated with a sub-page memory region spanning multiple cache lines, wherein determining if the agent has ownership of the first superline includes reading an entry for the first superline from an on-die superline directory table cache and reading an entry for the first superline from the on-die superline directory table cache includes reading an ownership bit associated with the agent;
• accessing the virtual memory address from the agent without triggering a snoop request when the agent has ownership of the first superline;
• and
• sending a region snoop request to acquire ownership of the first superline when the agent does not have ownership of the first superline.