Method and apparatus for managing data transfer in a computer memory

• US 20060112136A1
• Filed: 11/22/2005
• Published: 05/25/2006
• Est. Priority Date: 11/24/2004
• Status: Active Grant

• Current Assignee: Hewlett Packard Enterprise Development LP (Hewlett-Packard Enterprise Company)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Shankar, Ganesh Handige, Medikari, Anand S.
• Granted Patent: US 8,108,560 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/0709 in a distributed system consisting of a plurality of standalone computer nodes, e.g. clusters, client-server systems
• CPC Class Codes: G06F 11/073 in a memory management context, e.g. virtual memory or cache management memory management G06F12/00; testing of static memory units G11C29/00
• CPC Class Codes: G06F 11/076 by exceeding a count or rate limit, e.g. word- or bit count limit
• CPC Class Codes: G06F 11/0793 Remedial or corrective actions recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40
• CPC Class Codes: G06F 9/544 Buffers; Shared memory; Pipes

Abstract

The present invention relates to a method and apparatus for managing data transfer in a computer memory in which during the transfer of data from an application buffer to a network socket, memory usage faults are reduced.

Claims

1. A method for managing data transfer in a computer memory comprising the steps of:

a) transferring data from an application program memory to a network stack using zero copy data transfer;

b) monitoring the number of potential copy on write (COW) faults generated during said transfer of data for said application program; and

c) controlling the transferring of data so that if the number of potential COW faults exceeds a predetermined threshold for said application then in subsequent data transfers from said application program, data is copied to another memory location before transferring said data to said network stack.

2. A method according to claim 1 in which in step a) the zero copy data transfer is provided by page remapping.

3. A method according to claim 1 in which in step b) said monitoring is carried out for a plurality of application programs and the results of said monitoring are recorded in a record.

4. A method according to claim 3 in which the record entry for each application includes the port number, number of writes to the socket and the number of potential COW faults associated with said application.

5. A method according to claim 1 in which said other memory is kernel memory.

6. A method according to claim 1 in which said monitoring and controlling steps are carried out by the networking or socket code.

7. A method according to claim 1 further comprising the step of:

d) if the number of potential COW faults for said application falls below said predetermined threshold then in subsequent data transfers reverting to the use of zero copy data transfer.

8. A method according to claim 1 in which the threshold is determined by the percentage of data transfers that produce potential COW faults for a given application.

9. A method according to claim 8 in which the threshold is 30%.

10. A method according to claim 7 in which the threshold is 50%.

13. Apparatus according to claim 1 in which said monitoring means is operable to monitor a plurality of application programs and the results of said monitoring are recorded in a record

14. Apparatus according to claim 13 in which the record entry for each application includes the port number, number of writes to the socket and the number of potential COW faults associated with said application.

21. A computer program or group of computer programs arranged to enable a computer or group of computers to carry out the method of claim 1.

11. Apparatus for managing data transfer in a computer memory comprising:

a) transfer means operable to transfer data from an application program memory to a network stack using zero copy data transfer;

b) monitoring means operable to monitor the number of potential copy on write (COW) faults generated during said transfer of data for said application program; and

c) control means operable if the number of potential COW faults exceeds a predetermined threshold for said application to control subsequent data transfers from said application program so that data is copied to another memory location before transferring said data to said network stack.

12. Apparatus according to claim 11 in which the zero copy data transfer is provided by page remapping.

15. Apparatus according to claim 11 in which said other memory is kernel memory.

16. Apparatus according to claim 11 in which said monitoring and controlling means are provided by the networking or socket code.

17. Apparatus according to claim 11 in which the control means is further operable, if the number of potential COW faults for said application falls below said predetermined threshold, to revert to the use of zero copy data transfer in subsequent data transfers.

18. Apparatus according to claim 11 in which the threshold is determined by the percentage of data transfers that produce potential COW faults for a given application.

19. Apparatus according to claim 18 in which the threshold is 30%.

20. Apparatus according to claim 17 in which the threshold is 50%.

22. A computer program or group of computer programs arranged to enable a computer or group of computer provide the apparatus of claim 11.

23. A method of controlling data transfer between an application program layer and a socket layer in a Unix operating system comprising:

a) transferring data using zero copy transfer;

b) monitoring the number of actual copy on write (COW) faults generated by an application; and

c) if the monitored number of COW faults exceeds a threshold for said application then transferring subsequent data using normal copy transfer.

24. A method according to claim 23 in which in step b) the potential COW faults are monitored and used in step c).