Low overhead exclusive control for shared memory objects

• US 10,579,550 B2
• Filed: 11/01/2017
• Issued: 03/03/2020
• Est. Priority Date: 04/05/2017
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Katayama, Yasunao
• Primary Examiner(s): Henderson, Esther B.
• Application Number:
  US15/800,863
• Publication Number:
  US 20180293188A1
• Time in Patent Office: 853 Days
• CPC Class Codes: G06F 13/1642 with request queuing
• CPC Class Codes: G06F 13/1663 Access to shared memory
• CPC Class Codes: G06F 13/1668 Details of memory controller
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence
• CPC Class Codes: G06F 13/42 Bus transfer protocol, e.g. handshake; Synchronisation
• 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
• CPC Class Codes: G06F 9/544 Buffers; Shared memory; Pipes

Abstract

A computer-implemented method is provided for exclusive control of shared memory objects. The method computer-implemented includes transmitting and performing a plurality of accesses to the shared memory objects from local and remote locations via read requests and write requests made to a memory, and controlling the read and write requests by a memory controller including a read queue, a write queue, and a lock address list. The computer-implemented method further includes initiating each read request to the memory via the memory controller whatever the corresponding lock bit is, initiating each write request to the memory from the recently read location via the memory controller when the corresponding lock bit is enabled, otherwise notify the requesting local or remote locations as incomplete, and enabling and disabling the corresponding lock bit after the initiation of the read and write requests to the memory, respectively.

Claims

1. A computer-implemented method for exclusive control of shared memory objects, the method comprising:

transmitting and performing a plurality of accesses to the shared memory objects from local and remote locations via read requests and write requests made to a memory;

controlling the read and write requests by a memory controller incorporating therein a read queue, a write queue, and a lock address list, each slot of the lock address list associated with a lock bit;

initiating each read request to the memory via the memory controller whatever the corresponding lock bit is and changing status of corresponding slot to lock (reserve);

initiating each write request to the memory from a recently read location via the memory controller when the corresponding lock bit is enabled, otherwise notify the requesting local or remote locations as incomplete, and changing status of corresponding slot to unlocked; and

enabling the corresponding lock bit after the initiation of the read request to the memory and disabling the corresponding lock bit after the initiation of the write request to the memory.

2. The method of claim 1, wherein exclusive access controls with states and queues are handled near the memory.

3. The method of claim 2, wherein the exclusive access controls are for inter-node and intra-node communications.

4. The method of claim 1, wherein the memory controller arbitrates local and remote locations more equally.

5. The method of claim 1, wherein read-write constraints for multiple access is handled locally.

6. The method of claim 1, wherein the lock bits are segmented according to the memory controller'"'"'s access granularity.

7. The method of claim 1, wherein memory-based protocols executed by the memory controller are supported for IO memory access architectures such as Remote Direct Memory Access (RDMA).

8. A computer-implemented method for exclusive control of shared memory objects, the method comprising:

transmitting and performing a plurality of accesses to the shared memory objects from local and remote locations via read requests and write requests made to a memory;

controlling the read and write requests by a memory controller incorporating therein a read queue, a write queue, and a lock address list, each slot of the lock address list associated with a lock bit;

initiating each read request to the memory via the memory controller when the corresponding lock bits are disabled and changing status of corresponding slot to lock (reserve);

initiating each write request to the memory from a recently read location via the memory controller when the corresponding lock bits are enabled, and changing status of corresponding slot to unlocked; and

enabling the corresponding lock bit after the initiation of the read request to the memory and disabling the corresponding lock bit after the initiation of the write request to the memory.

9. The method of claim 8, wherein exclusive access controls with states and queues are handled near the memory.

10. The method of claim 9, wherein the exclusive access controls are for inter-node and intra-node communications.

11. The method of claim 8, wherein the memory controller arbitrates local and remote locations more equally.

12. The method of claim 8, wherein read-write constraints for multiple access is handled locally.

13. The method of claim 8, wherein the lock bits are segmented according to the memory controller'"'"'s access granularity.

14. The method of claim 8, wherein memory-based protocols executed by the memory controller are supported for 10 memory access architectures such as Remote Direct Memory Access (RDMA).