System and method for transferring updates from virtual frame buffers

• US 8,073,990 B1
• Filed: 09/23/2009
• Issued: 12/06/2011
• Est. Priority Date: 09/23/2008
• Status: Active Grant

• Current Assignee: Teradici Corporation (HP Inc.)
• Original Assignee: Teradici Corporation (HP Inc.)
• Inventors: Quinton, Bradley Reginald, Baron, Charles Peter, Doucette, Daniel Jean Donat, Helter, Paul Andrew
• Primary Examiner(s): Tsai, Henry
• Assistant Examiner(s): RHU, KRIS M
• Application Number:
  US12/586,498
• Time in Patent Office: 804 Days
• Field of Search: None
• US Class Current: 710/22
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence

Abstract

A method and apparatus for transferring data from a first to a second memory of a computer system. The method comprises (i) initializing a descriptor with a description of physical addressing of a first section of a first array of the first memory; (ii) updating a mask associated with the descriptor with an indication for transferring data from a first sub-section of the first section to the second memory, the mask and the data managed by an application on a first virtual machine of the computer system, the application isolated from the physical addressing of the first section; (iii) responsive to the updated mask, (a) determining physical addresses of the first sub-section based on the description, and (b), transferring the data from the first sub-section to the second memory; and (iv) clearing at least a portion of the updated mask to indicate completion of transferring the data.

Claims

1. A method for transferring data from a first computer memory of a computer system to a second computer memory of the computer system, at least a portion of the method being performed by the computer system comprising at least one processor, the method comprising:

(i) initializing a descriptor with a description of physical addressing of a first two dimensional (2D) section of a first 2D data array of the first computer memory;

(ii) updating a mask associated with the descriptor with an indication for transferring image data from a first 2D sub-section of the first 2D section to the second computer memory, the mask and the image data managed by an application on a first virtual machine of the computer system, the application isolated from the physical addressing of the first 2D section;

(iii) responsive to the updated mask, (a) determining physical addresses of the first 2D sub-section based on the description of physical addressing, and (b) transferring the image data from the first 2D sub-section to the second computer memory; and

(iv) clearing at least a portion of the updated mask to indicate completion of transferring the image data to the second computer memory.

2. The method of claim 1, wherein transferring the image data comprises at least one of:

leaving the image data of the first computer memory unchanged;

storing a modified instance of the image data in the second computer memory, the modified instance of the image data comprising at least one of a data structure change or encoded data;

or

transferring the image data via a processor expansion bus.

3. The method of claim 1, wherein the description of physical addressing comprises a dimension of the first 2D section, a base physical address of the first 2D section, an address pitch of the first 2D section, and a list of physical page addresses of the first 2D section.

4. The method of claim 3, wherein determining the physical addresses comprises:

selecting page addresses from the list of physical page addresses;

determining physical page address offsets based on the mask and the address pitch; and

aggregating addresses of the transferring the image data to support burst transfers over a processor expansion bus.

5. The method of claim 1, further comprising (vi) initializing each descriptor of a plurality of descriptors with a different description of physical addressing of a different 2D section from a plurality of 2D sections of a plurality of 2D data arrays, wherein each 2D data array of the plurality of 2D data arrays is associated with a different virtual machine operating in the computer system.

6. The method of claim 5, further comprising, subsequent to step (vi), repeating steps (ii), (iii) and (iv) for descriptors of the plurality of descriptors that are associated with selective 2D sub-sections of the plurality of 2D sections.

7. The method of claim 6, wherein repeating steps (ii), (iii), and (iv) comprises determining an availability of processing resources associated with each 2D data array in the plurality of 2D data arrays.

8. The method of claim 7, wherein the processing resources comprise image encoding and communicating resources, the processing resources managed by a peripheral system comprising the second computer memory.

9. The method of claim 6, further comprising, subsequent to step (ii), processing the plurality of descriptors to determine the updated mask, wherein the plurality of descriptors are organized as a list of descriptors.

10. The method of claim 1, wherein the mask is accessible to the first virtual machine, and wherein the descriptor is protected from access by the first virtual machine.

11. The method of claim 1, wherein the first 2D data array comprises an unaligned subset of a larger 2D data array, and the first 2D sub-section is rectangular with dimensions of at least 8×

8 pixels.

12. The method of claim 1, wherein the descriptor comprises the mask, and wherein the image data is transferred in an order suitable for processing by a peripheral system comprising the second computer memory.

13. A system for transferring data from a selection of two dimensional (2D) sub-sections of a plurality of 2D data arrays, the system comprising:

a computer memory enabled to store (i) the plurality of 2D data arrays, wherein the plurality of 2D data arrays comprises a plurality of physical memory pages with autonomous physical addressing, (ii) a plurality of descriptors comprising address information of the autonomous physical addressing and dimensional information of the plurality of 2D data arrays, and (iii) a plurality of masks comprising change indicia for identifying the selection of 2D sub-sections;

a Direct Memory Access (DMA) controller, coupled to the computer memory, enabled to (iv) determine the selection of 2D sub-sections based on an indication of readiness to process the selection of 2D sub-sections and the change indicia in the plurality of masks, (v) read the plurality of descriptors to obtain the address information and the dimensional information, and (vi) generate transfer operations based on the address information and the dimensional information; and

a peripheral system, coupled to the computer memory, enabled to (vii) receive image data from the selection of 2D sub-sections resulting from the transfer operations, and (viii) generate the indication of readiness.

14. The system of claim 13, wherein the DMA controller generates the transfer operations by calculating physical addresses of the selection of 2D sub-sections based on the address information and the dimensional information.

15. The system of claim 14, wherein the address information comprises page addresses and offset values, and the dimensional information comprises a pitch value.

16. The system of claim 13, wherein the autonomous physical addressing is isolated from a logical addressing of the plurality of 2D data arrays, the logical addressing used in generating data for the plurality of 2D data arrays;

the peripheral system comprises the DMA controller; and

generating the transfer operations comprises determining sections of the plurality of physical memory pages associated with the selection of 2D sub-sections.