Appeal No. 2000-1238
Application 08/566,638
resource. "The semaphore ownership table 24 consists of a number
of sections, one for each node. Each section has a fixed number
of slots, each of which can hold an entry, defining the ownership
state of a particular semaphore." Column 3, ll. 19-22.
Specifically, each entry in the ownership table includes the
following two fields: (1) ADDRESS, which is the virtual address
of the semaphore location to which the entry relates; and
(2) STATE, which is the ownership state of the semaphore location
(col. 3, ll. 23-28). The meanings of the ownership states are
defined as follows:
IDLE: the semaphore is not owned by any node.
OWNED: the semaphore is owned by the local node.
DISCARD: ownership of the semaphore has been relinquished.
OTHER-OWNED: the semaphore is owned by a remote node.
QUEUED: the semaphore has one or more suspended semaphore
operations in the queue 25.
Column 3, ll. 39-47. It is evident from these ownership state
definitions and the abstract, reproduced in part below, that a
semaphore cannot be concurrently owned by plural nodes:
When a node requires a semaphore operation on a
particular semaphore, a semaphore message is broadcast
to all the nodes instructing them to perform the
semaphore operation on their local copies of the
semaphore. If the semaphore is unowned, the node must
suspend the semaphore operation until the message
returns, so as to ensure correct chronology for the
semaphore operation. If, however, the semaphore [is]
owned by this node, the node can perform the semaphore
operation without waiting for the message to return.
This speeds up the semaphore mechanism. If the
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