Systems and methods for controlling access to a shared data structure with reader-writer locks using multiple sub-locks

Abstract

A computer system for controlling access to a shared data structure includes a shared memory coupled to first and second processing units that stores a multi-lock to control access to a shared data structure. The multi-lock includes a first sub-lock associated with the first processing unit and a second sub-lock associated with the second processing unit The system also includes a data access control engine to receive a request to read from the data structure from the first processing unit and, as a result, determine whether a privately modifiable copy the first sub-lock exists in a first cache dedicated to the first processing unit, acquire a read portion of the first sub-lock and not communicate the acquisition across a coherence bus if a privately modifiable copy of the first sub-lock exists in the first cache, and if a privately modifiable copy of the first sub-lock does not exist in the first cache, load the first sub-lock into the first cache if no copy is in the first cache, shootdown other copies of the first sub-lock, and acquire the read portion of the first sub-lock.