Method and system for queue descriptor cache management for a host channel adapter

A host channel adaptor (HCA), comprising:

• a descriptor fetch module, comprising:
• a queue descriptor cache, configured to store a copy of a queue descriptor comprising a plurality of data describing a queue,
• wherein the queue descriptor is located in a memory of a host operatively connected to the HCA, and
• wherein the queue is located in the memory and comprises a plurality of entries;
• and
• a cache control module, configured to:
• obtain the copy of the queue descriptor from the memory,
• store the copy of the queue descriptor in the cache,
• determine that the HCA has accessed the queue,
• calculate a value representing a utilization of the queue,
• compare the value against a threshold, and
• fetch a new copy of the queue descriptor from memory when the value exceeds the threshold;
• and
• a plurality of additional modules, configured to:
• access the copy of the queue descriptor to obtain the plurality of data;
• access, using the plurality of data, the queue;
• and
• update the plurality of data to reflect the access to the queue.

A system comprising:

• a host, comprising:
• a processor, and
• a memory configured to store:
• a queue descriptor comprising a plurality of data describing a queue, comprising:
• a hardware pointer configured to reference an entry in the queue most recently access by the HCA,
• a software pointer configured to reference an entry in the queue most recently accessed by a host, and
• a threshold;
• and
• a queue comprising a plurality of entries;
• and
• a host channel adapter (HCA) operatively connected to the host and comprising:
• a cache configured to store a copy of the queue descriptor, and
• a cache control module, configured to:
• obtain the copy of the queue descriptor from the memory;
• store the copy of the queue descriptor in the cache;
• determine that the HCA has accessed the queue;
• calculate a value representing the number of entries separating the software pointer and the hardware pointer;
• compare the value against the threshold;
• and
• fetch a new copy of the queue descriptor from the memory when the value exceeds the threshold;
• and
• a plurality of additional modules, configured to:
• access the copy of the queue descriptor to obtain the plurality of data;
• access, using the plurality of data, the queue;
• and
• update the plurality of data to reflect the access to the queue.