Back to results
US 5,301,333 AGranted
Tree structured variable priority arbitration implementing a round-robin scheduling policy
AssigneeBell Communications Research, Inc.
InventorKuo-Chu Lee
Life of this patent
Estimating the term…
Abstract
An inventive arbiter controls access to a resource in a high speed computer or telecommunications network. The arbiter is capable of performing round-robin scheduling for N requests with P possible priority levels with a sublinear time complexity. The high arbitration speed is achieved through use of a tree structure with a token distribution system for implementing the round-robin scheduling policy.
Claims13
A method implemented in a tree-structured arbiter circuit for controlling access to a resonance in an electronic network comprising the steps of
- during an arbitration cycle, receiving at a plurality of leaf nodes of the tree-structured arbiter circuit a plurality of requests, each request having a token bit and being from a plurality of priority classes for said resonance,
- in a contention resolution phase of said arbitration cycle, determining, at each of a plurality of non-leaf nodes of the tree-structured arbiter circuit, priority information by executing a contention resolution algorithm and transmitting said priority information up the tree-structured arbiter circuit so that a winning request is determined at a root node of the tree-structured arbiter circuit, and
- in a token redistribution phase of said arbitration cycle, determining, at each non-leaf node, token redistribution information by executing a token redistribution algorithm and transmitting the token redistribution information down the tree-structured arbiter circuit to the leaf nodes so that said leaf node receiving said winning request receives a lower priority than other said leaf nodes having the same priority in a next arbitration cycle to implement a round-robin policy for serving requests at said leaf nodes.
A method implemented in a tree-structured arbiter circuit for controlling access to a resource in an electronic network comprising the steps of
- serving at a plurality of leaf nodes of the tree-structured arbiter circuit a plurality of access requests, N, of different priority classes in an arbitration cycle, each access request having a token bit,
- determining at each of a plurality of non-leaf nodes of the tree-structured arbiter circuit priority information by executing a contention resolution algorithm and transmitting the priority information up the tree-structured arbiter circuit so that a winning request from the highest of said priority classes is determined at a root node of the tree-structured arbiter circuit, and
- determining a relative priority of the leaf node which provided the winning request and the other leaf nodes serving said access requests of the same priority class for a next arbitration cycle so that said plurality of leaf nodes serving said access requests of the highest priority class achieve fair access to said resource, said relative priority determining step including determining at each said non-leaf node token redistribution information by executing a token redistribution algorithm and distributing the token redistribution information down the tree-structured arbiter circuit to the leaf nodes such that the leaf node which provided the winning request receives a lower priority than other leaf nodes having the same priority to implement a round-robin scheduling policy among the leaf nodes serving requests of the highest priority class.
An arbiter circuit for controlling access to a resource in an electronic network comprising
- a plurality of leaf and non-leaf nodes arranged in a tree structure, each of said non-leaf nodes being connected to two child nodes below it in the tree structure and one parent node above it in the tree structure, said leaf nodes serving a plurality of access requests, of differing priority classes and each request having an associated token bit,
- each of said non-leaf nodes including means for receiving two of said access requests from the two child nodes connected below it in the tree structure and means for executing a contention resolution algorithm to determine priority between the two received requests so that a winning request is determined at the uppermost node in said tree, said winning request being chosen from the highest of said priority classes, means for executing a token redistribution algorithm for determining token redistribution information to be transmitted to said leaf nodes, and means for implementing said token distribution information to clear said token bit of said winning request such that the leaf node serving said winning request receives a lower priority than other leaf nodes in the same priority class to implement a round-robin scheduling policy among the leaf nodes serving said access requests of the highest priority class.
Dependencies are inferred from the claim text.