A memory system is disclosed in which hardware assisted leases are utilized
to control access to shared data resources among data users. The lease is
a type of lock on content in the memory system that automatically expires
after a preset period of time. The lease enables the lease owner exclusive
use of the associated content in the memory system. Furthermore, the
memory system has a memory access mechanism that is separate from the data
users. The memory access mechanism includes hardware components to enforce
lease-based access to the memory system. Since the lease expires rather
than being permanently granted, no CPU or software thread is able to
monopolize a lease forever. Moreover, since the lease-base access is
hardware-assisted, faulty CPUs or software are prevented from unauthorized
access to leased (or locked) content in which another CPU or software
already holds a lease.
