Updating training data

A method of operating an apparatus comprising training storage circuitry configured to store one or more training entries, each of the one or more training entries comprising training data indicative of a trigger memory access request to a local storage structure and one or more relationships between the trigger memory access request and subsequent memory access requests to the local storage structure, wherein the training data is suitable to be used for generation of speculative memory access requests for retrieval of data into the local storage structure by a predictive structure in response to observation of the trigger memory access request, the method comprising:

• generating a filtered sequence of memory access requests by applying a filter to a sequence of memory access requests to the local storage structure;
• for each given memory access request of the sequence of memory access requests that resulted in a hit on a data item in the local storage structure, including the given memory access request in the filtered sequence of memory access requests in dependence on a filter criterion, wherein the filter criterion is independent of a type of request that resulted in the data item being allocated into the local storage structure;
• monitoring the filtered sequence of memory access requests;
• and
• in response to observation of the trigger memory access request indicated in a training entry of the one or more training entries, updating the training data in the training entry based on the filtered sequence of memory access requests.

A non-transitory computer-readable medium storing computer-readable code for fabrication of an apparatus comprising:

• training storage circuitry configured to store one or more training entries, each of the one or more training entries comprising training data indicative of a trigger memory access request to a local storage structure and one or more relationships between the trigger memory access request and subsequent memory access requests to the local storage structure, wherein the training data is suitable to be used for generation of speculative memory access requests for retrieval of data into the local storage structure by a predictive structure in response to observation of the trigger memory access request;
• filter circuitry configured to generate a filtered sequence of memory access requests by applying a filter to a sequence of memory access requests to the local storage structure;
• and
• training circuitry configured to monitor the filtered sequence of memory access requests, and responsive to observation of the trigger memory access request indicated in a training entry of the one or more training entries, to update the training data in the training entry based on the filtered sequence of memory access requests,
• wherein:
• the filter circuitry is configured for each given memory access request of the sequence of memory access requests that resulted in a hit on a data item in the local storage structure, to include the given memory access request in the filtered sequence of memory access requests in dependence on a filter criterion;
• and
• the filter criterion is independent of a type of request that resulted in the data item being allocated into the local storage structure.