Synchronization with partial memory replication

• US 7,739,349 B2
• Filed: 10/05/2007
• Issued: 06/15/2010
• Est. Priority Date: 10/05/2006
• Status: Active Grant

• Current Assignee: Waratek Limited (Waratek Holdings Ltd.)
• Original Assignee: Waratek Pty Limited
• Inventors: Holt, John M.
• Primary Examiner(s): Chea; Philip J
• Application Number:
  US11/973,326
• Publication Number:
  US 20080126508A1
• Time in Patent Office: 984 Days
• Field of Search: 709/201, 709/213, 709/205, 711/147, 711/148
• US Class Current: 709/213
• CPC Class Codes: G06F 2209/522 Manager
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms

Abstract

A multiple computer system is disclosed in which the local memory of each computer (M1, M2, . . . Mn) can be different having some memory locations (A, B) which are replicated in other computers and other memory locations (E) which are not. When any computer seeks to acquire or release a synchronizing lock a check (171, 181) is made to see if the relevant memory location is present on any other machine. If yes, synchronization is carried out. However, if no, then no synchronization is required and the synchronizing procedures are by-passed.

Claims

1. A multiple computer system comprising:

a plurality of computers all interconnected via a communications network;

each of said plurality of computers having a local memory and each of said plurality of computers operating a corresponding different portion of an applications program written to be executed only on a single computer, said local memory of each said computer not necessarily being identical, at least some memory locations of each said computer being replicated in at least one other of said computers, and said local memory of each said computer being independent such that all memory read requests of each said computer are satisfied by reading the independent local memory of the requesting computer; and

each of said plurality of computers includes a check means for checking, prior to acquiring or releasing a synchronizing lock on a specific local memory location, to determine if that memory location is replicated in the local memory of any other of said plurality of computers, said check means by-passing said lock acquisition or release only if said specific memory location is not replicated on at least one other computer.

2. The multiple computer system as in claim 1, wherein a look-up table listing said memory locations and said computers is available to said check means.

3. The multiple computer system as in claim 2, wherein said look-up table is located in a server computer.

4. The multiple computer system as in claim 1, wherein said look-up table is located in a server computer.

5. The multiple computer system as in claim 2, wherein said look-up table is implemented as a synchronizing lock data structure comprising:

a look-up table storing a plurality of memory location identifiers for independent local memory locations in each of a plurality of computers; and

a replication indicator for indicating if a memory location for which it is desired to acquire or release a synchronizing lock is then currently replicated in the local memory of any other one of the plurality of computers.

6. The multiple computer system as in claim 1, further comprising a data structure query means for querying a data structure to determine if a memory location for which it is desired to acquire or release a synchronizing lock is then currently replicated in the local memory of any other one of the plurality of computers.

7. The multiple computer system as in claim 5, wherein each of said plurality of computers is loaded with a computer program product stored in a computer readable media, the computer program including executable computer program instructions and adapted for execution in a processor within a computer or information appliance and a memory coupled with the processor to modify the operation of the computer or information appliance, for modifying the operation of each of the plurality of computers;

the modification of operation including performing a method of controlling the acquiring and/or releasing of a synchronizing lock, said method comprising;

(i) prior to acquiring or releasing a synchronizing lock on a specific local memory location checking to determine if that memory location is replicated in the local memory of any other computer; and

(ii) by-passing acquiring or releasing said lock only if said specific memory location is not replicated on at least one other computer.

8. The multiple computer system as in claim 7, wherein the computer program product further includes instructions for performing the method including the further step of:

(iii) carrying out step (i) including by consulting a look-up table listing said memory locations and said computers.

9. The multiple computer system as in claim 8, wherein the computer program product further includes instructions for performing the method including the further step of:

(iv) maintaining said look-up table in a server computer.

10. At least one computer adapted to co-operate with other computers so as to form a multiple computer system as defined in claim 1.