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US 7,353,342 B1Granted
Shared lease instruction support for transient blocking synchronization
AssigneeSun Microsystems, Inc.
InventorsDaniel S. Nussbaum, Mark S. Moir, Nir N. Shavit, Guy L. Steele
Life of this patent
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Abstract
A computer system implementing transient blocking synchronization allows a memory location leased by a first process to be read-accessible to another process. In other words, more than one thread may have read-only type leases on a given memory location at a given time. Such “shared” leases expire when respective lease periods of the shared leases elapse.
Claims3
A method of performing computer system operations, comprising:
- obtaining a shared lease to a first memory location in a shared memory, wherein the shared lease is for a first predetermined period of time, and wherein an exclusive bit associated with the shared lease is not set;
- extending the shared lease to the first memory location for a second predetermined amount of time;
- setting the exclusive bit responsive to an attempt to obtain an exclusive lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
- denying the attempt to obtain the exclusive lease;
- attempting to extend the shared lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
- denying the attempt to extend the shared lease when the exclusive bit associated with the shared lease is set;
- and
- releasing the shared lease after the second predetermined amount of time.
5 more elements
A shared-memory multiprocessor computer system having instructions for synchronizing operations on memory, the instructions comprising instructions to:
- obtain a shared lease to a first memory location in a shared memory, wherein the shared lease is for a first predetermined period of time, and wherein an exclusive bit associated with the shared lease is not set;
- extend the shared lease to the first memory location for a second predetermined amount of time;
- set the exclusive bit responsive to an attempt to obtain an exclusive lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
- deny the attempt to obtain the exclusive lease;
- attempt to extend the shared lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
- deny the attempt to extend the shared lease when the exclusive bit associated with the shared lease is set;
- and
- release the shared lease after the second predetermined amount of time.
5 more elements
A computer system, comprising:
- at least one processor;
- a shared memory operatively connected to the at least one processor and comprising at least a first memory location and a second memory location shared by a plurality of processes;
- and
- a controller configured to:
- obtain a shared lease to the first memory location for a first predetermined period of time,
- wherein a first value in the first memory location is used to calculate a second value,
- wherein the second value is stored in the second memory location, and
- wherein an exclusive bit associated with the shared lease is not set;
- extend the shared lease to the first memory location for a second predetermined amount of time;
- set the exclusive bit responsive to an attempt to obtain an exclusive lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
- deny the attempt to obtain the exclusive lease;
- attempt to extend the shared lease to the first memory location, wherein the attempt is made within the second predetermined period of time;
- deny the attempt to extend the shared lease when the exclusive bit associated with the shared lease is set;
- and
- release the shared lease after the second predetermined amount of time.
12 more elements
Dependencies are inferred from the claim text.