| 摘要 |
A computer processor includes a number of register pairs LOCKADD/LOCKCOUNT to hold values identifying when a computer resource is locked. The LOCKCOUNT register is incremented or decremented in response to lock or unlock instructions, respectively. The lock is freed when a count associated with the LOCKCOUNT register is decremented to zero. In embodiments without LOCKOUT registers, the lock may be freed on any unlock instruction corresponding to the lock. In some embodiments, a computer object includes a header in which two header LSBs store: (1) a LOCK bit indicating whether the object is locked, and (2) a WANT bit indicating whether a thread is waiting to acquire a lock for the object. |
