Testing a data coherency algorithm

A method of testing a data coherency algorithm of a multi-processor environment, wherein a simulated multi-processor environment containing a private cache hierarchy and simulation drivers for other components of the multi-processor environment is provided, the method comprising:

• implementing a global time incremented on a processor cycle and used for timestamping;
• implementing a transactional execution flag representing a processor core guaranteeing atomicity and coherency of currently executed instructions;
• implementing a transactional footprint, the transactional footprint keeping an address of each cache line that was used by the processor core, while the processor core is guaranteeing the atomicity and coherency of a transaction;
• implementing a reference model, the reference model operating on a cache line and keeping a set of timestamps for the cache line, the set comprising a construction date representing a first global timestamp when new data arrives at the private cache hierarchy, and an expiration date representing a second global timestamp when the private cache hierarchy is hit by a cross-invalidation;
• implementing a core observed timestamp representing a global timestamp, which is an oldest construction date of data used before;
• implementing interface events that monitor at least one of:
• a fetch return from the simulated multi-processor environment to update the construction date;
• a fetch return from an L1 cache to the processor core to update the core observed timestamp;
• a cross-invalidate from the simulated multi-processor environment to update the expiration date;
• a transaction start instruction being executed by the processor core to update the transactional execution flag and clear the transactional footprint;
• or
• a transaction end instruction being executed by the processor core to perform the checking;
• and
• reporting an error based on detecting a transaction end event and finding a cache line in the transactional footprint with an expiration date that is older than or equal to a core observed time.