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US 2004/0003180 A1Published application
System with a directory based coherency protocol and split ownership and access right coherence mechanism
AssigneeSun Microsystems, Inc.
InventorRobert E. Cypher
Life of this patent
Estimating the term…
Abstract
Various systems and methods for using a directory based coherency protocol in a system that employs a split ownership and access right cache coherence mechanism are disclosed. A computer system may include a directory, several active devices configured to access data, an address network configured to convey coherence requests point-to-point between the active devices and the directory, and a data network configured to convey data between the active devices. Each active device includes a cache configured to store data accessed by that active device. An ownership responsibility and an access right associated with a first coherency unit in a first cache transition at different times.
Claims17
A computer system comprising:
- a plurality of active devices, wherein the plurality of active devices includes a first active device, wherein the first active device includes a first cache configured to store data accessed by the first active device;
- a directory configured to indicate which of the plurality of active devices has an ownership responsibility for a given coherency unit;
- an address network for conveying address packets point-to-point between the plurality of active devices and the directory;
- a data network for conveying data packets between the plurality of active devices;
- wherein the first active device is configured to transition an ownership responsibility for a first coherency unit cached in the first cache upon receipt of a first address packet and to transition an access right to the first coherency unit cached in the first cache upon receipt of a corresponding data packet, wherein the ownership responsibility transitions at a different time than the access right transitions.
2 more elements
A method for maintaining coherency in a computer system comprising:
- a first active device initiating a first coherence transaction for a first coherency unit in a first cache by sending a first address packet on an address network;
- conveying the first address packet point-to-point through the address network to a directory configured to indicate which of a plurality of active devices has an ownership responsibility associated with a given coherency unit;
- and
- the first active device transitioning an ownership responsibility for the first coherency unit cached in the first cache upon receiving a second address packet from the directory and transitioning an access right to the first coherency unit cached in the first cache upon receiving a corresponding data packet;
- wherein said transitioning the ownership responsibility occurs at a different time than said transitioning the access right.
2 more elements
A computer system comprising:
- means for storing ownership information associated with one or more coherency units;
- a plurality of means for accessing data, wherein each means for accessing data includes a cache for storing data accessed by that means for accessing data, wherein the plurality of means for accessing data includes a first means for accessing data, wherein the first means for accessing data includes a first cache;
- means for conveying coherence requests point-to-point between the plurality of means for accessing data and the means for storing ownership information;
- means for conveying data between the plurality of means for accessing data;
- wherein the first means transitions an ownership responsibility for a first coherency unit cached in the first cache upon receiving a first coherence request on the means for conveying coherence requests;
- wherein the first means transitions an access right to the first coherency unit cached in the first cache upon receiving corresponding data on the means for conveying data;
- wherein the access right transitions at a different time than the ownership responsibility transitions.
4 more elements
A computer system comprising:
- a plurality of active devices, wherein each active device includes a cache configured to store data accessed by that active device, wherein the plurality of active devices includes a first active device, wherein the first active device includes a first cache;
- a directory configured to indicate which one of the plurality of active devices has an ownership responsibility associated with a given coherency unit;
- an address network configured to convey a plurality of address packets point-to-point between the plurality of active devices and the directory;
- a data network configured to convey data between the plurality of active devices;
- wherein an access right to a first coherency unit in the first cache transitions in response to the first active device sending data corresponding to the first coherency unit on the data network.
2 more elements
Dependencies are inferred from the claim text.