SHARING DATA BY A VIRTUAL MACHINE

• US 20200133703A1
• Filed: 10/30/2018
• Published: 04/30/2020
• Est. Priority Date: 10/30/2018
• Status: Active Grant

• Current Assignee: Blackberry Limited
• Original Assignee: 2236008 Ontario Inc. (Blackberry Limited)
• Inventors: SUN, Xiaoyong, NEFEDOV, Mikhail
• Granted Patent: US 10,956,240 B2
• Time in Patent Office: Days
• CPC Class Codes: G06F 2009/45583 Memory management, e.g. access or allocation
• CPC Class Codes: G06F 3/0604 Improving or facilitating administration, e.g. storage management
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0647 Migration mechanisms
• CPC Class Codes: G06F 3/0656 Data buffering arrangements
• CPC Class Codes: G06F 3/0664 at device level, e.g. emulation of a storage device or system
• CPC Class Codes: G06F 3/067 Distributed or networked storage systems, e.g. storage area networks [SAN], network attached storage [NAS]
• CPC Class Codes: G06F 9/455 Emulation; Interpretation; Software simulation, e.g. virtualisation or emulation of application or operating system execution engines
• CPC Class Codes: G06F 9/45558 Hypervisor-specific management and integration aspects
• CPC Class Codes: G06F 9/54 Interprogram communication
• CPC Class Codes: G06F 9/544 Buffers; Shared memory; Pipes

Abstract

A memory block is provided that is shared between two endpoints. This first endpoint is either a host for a virtual machine or the virtual machine. The second endpoint is either the host or another virtual machine. The shared memory block includes a buffer, a post counter, and an acknowledgment counter. The block is employed for communicating data from the first endpoint to the second endpoint. Sending data to the second endpoint includes identifying the buffer as being currently owned by the first endpoint and storing data in the buffer. It is then detected that the acknowledgment counter is equal to the post counter. The post counter is then incremented to signal that data has been stored for receipt by the second endpoint. Receiving the data by the second endpoint includes detecting that the post counter has changed and then incrementing the acknowledgment counter to acknowledge receipt of the data.

Claims

1. A computer-implemented method comprising:

providing a memory block shared between a first endpoint and a second endpoint, the shared memory block including at least one buffer, a post counter, and an acknowledgment counter, and the first endpoint being one of a host for a virtual machine hosted by a computing device or the virtual machine, and the second endpoint being one of the host or another virtual machine hosted by the computing device;

sending, by the first endpoint, data to the second endpoint, the sending including;

identifying one of the at least one buffers as being currently owned by the first endpoint and storing data in that buffer;

detecting that the acknowledgment counter is equal to the post counter; and

following detecting that the acknowledgment counter is equal to the post counter, incrementing the post counter to signal that data has been stored for receipt by the second endpoint;

receiving, by the second endpoint, the data from the first endpoint, the receiving including;

detecting that the post counter has changed; and

following detecting that the post counter has changed, incrementing the acknowledgment counter to acknowledge receipt of the data.

2. The method of claim 1 wherein at least one buffer includes a plurality of buffers and wherein the shared memory block further includes a posting buffer index, and wherein sending, by the first endpoint, data to the second endpoint, further includes:

following detecting that the acknowledgment counter is equal to the post counter and prior to incrementing the post counter, setting the posting buffer index to a value identifying the one of the buffers in which the data was stored, and

wherein receiving, by the second endpoint, the data from the first endpoint further includes;

following detecting that the post counter has changed, identifying, based on the posting buffer index, the one of the buffers as being the buffer storing data for receipt by the second endpoint.

3. The method of claim 2 wherein the shared memory block further includes a buffer ownership bitmap having bits identifying ownership of the plurality of buffers as between the first endpoint and the second endpoint and wherein identifying the one of the at least one buffers as being currently owned by the first endpoint includes determining, based on the buffer ownership bitmap, that the one of the at least one buffers is currently owned by the first endpoint.

4. The method of claim 3 wherein the receiving further includes:

prior to incrementing the acknowledgment counter, taking, by the second endpoint, ownership of the one of the at least one buffer by toggling the value of a bit of the buffer ownership bitmap corresponding to that buffer.

5. The method of claim 4, further comprising, the second endpoint:

after taking ownership of the one of the at least one buffers, processing the data stored in that buffer; and

after completing processing of the data stored in the one of the at least one buffers, releasing ownership of the one of the at least one buffer to the first endpoint by toggling the value of the bit of the buffer ownership bitmap corresponding to that buffer.

6. The method of claim 3, further comprising:

returning, by the second endpoint, ownership of a second one of the buffers to the first endpoint by toggling a value of a bit of the buffer ownership bitmap corresponding to the second one of the buffers.

7. The method of claim 3, further comprising:

prior to detecting that the acknowledgment counter is equal to the post counter, waiting for the acknowledgment counter to be equal to the post counter, and, while waiting for the acknowledgment counter to be equal to the post counter;

identifying, based on the buffer ownership bitmap, a second one of the buffers owned by the first endpoint; and

storing further data in the second one of the buffers.

8. The method of claim 2, further comprising:

sending, by the first endpoint, further data to the second endpoint, the sending of the further data including;

identifying a second one of the buffers as being owned by the first endpoint;

storing data in the second one of the buffers;

detecting that the acknowledgment counter is equal to the post counter;

following detecting that the acknowledgment counter is equal to the post counter;

setting the posting buffer index to a value identifying the second one of the buffers; and

incrementing the post counter to signal that data has been stored for receipt by the second endpoint;

receiving, by the second endpoint, the further data from the first endpoint, the receiving including;

detecting that the post counter has changed; and

following detecting that the post counter has changed, incrementing the acknowledgment counter to acknowledge receipt of the further data.

9. The method of claim 8, wherein the shared memory block further includes a buffer ownership bitmap having bits identifying ownership of the plurality of buffers as between the first endpoint and the second endpoint and wherein the receiving of the data further includes, prior to incrementing the acknowledgment counter, taking, by the second endpoint, ownership of the one of the at least one buffer by toggling the value of a bit of the buffer ownership bitmap corresponding to the one of the at least one buffer, and wherein the receiving of the further data includes, prior to, incrementing the acknowledgment counter, taking, by the second endpoint, ownership of the second one of the buffers by toggling the value of a bit of the buffer ownership bitmap corresponding to the second one of the buffers.

10. The method of claim 9, further comprising:

while the second one of the buffers is owned by the second endpoint, returning, by second endpoint, ownership of the one of the at least one buffer to the first endpoint by toggling a value of the bit of the buffer ownership bitmap corresponding to the one of the at least one buffer.

11. The method of claim 9, further comprising:

while the one of the at least one buffers is owned by the second endpoint, returning, by second endpoint, ownership of the second of the buffers to the first endpoint by toggling a value of the bit of the buffer ownership bitmap corresponding to the second one of the buffers.

12. The method of claim 1 wherein the at least one buffer includes only one buffer and wherein that buffer is owned by the first endpoint when the acknowledgment counter is equal to the post counter and wherein that buffer is owned by the second endpoint when the post counter is greater than the acknowledgment counter.

13. The method of claim 1 wherein detecting that the post counter has changed includes periodically polling the value of the post counter to determine whether the value of the post counter has changed.

14. The method of claim 1 further comprising, prior to detecting that the acknowledgment counter is equal to the post counter, waiting for the acknowledgment counter to be equal to the post counter, wherein waiting for the acknowledgment counter to be equal to the post counter includes periodically polling the value of the acknowledgment counter to determine whether the value of the acknowledgment counter has been incremented.

15. A computer system comprising:

at least one processor; and

a physical memory storing instructions that, when executed by the at least one processor, cause a first endpoint to communicate data to a second endpoint via a portion of the physical memory shared between the first endpoint and the second endpoint, the first endpoint being one of a host for a virtual machine hosted by the computer system or the virtual machine, and the second endpoint being one of the host or another virtual machine hosted by the computer system, the portion of the physical memory including;

at least one buffer;

a post counter incrementable by the first endpoint to signal to the second endpoint that data has been made available in one of the at least one buffers; and

an acknowledgment counter incrementable by the second endpoint to acknowledge signaling that data has been made available in one of the at least one buffers.

16. The computer system of claim 15, wherein the at least one buffer includes a plurality of buffers and wherein the portion of the physical memory further includes:

a posting buffer index modifiable by the first endpoint to indicate a particular one of the buffers in which data has been stored for communication to the second endpoint

a buffer ownership bitmap storing bits corresponding to the buffers, the bits identifying ownership of the plurality of buffers as between the first endpoint and the second endpoint.

17. The computer system of claim 15 wherein the buffers are of a uniform size.

18. The computer system of claim 15 wherein the data communicated by the first endpoint to the second endpoint is pixel data.

19. A non-transitory computer-readable storage medium storing instructions that, when executed by a processor of a computer system, cause a first endpoint to send data to a second endpoint using a memory block shared between the first endpoint and the second endpoint, the first endpoint being one of a host for a virtual machine hosted by the computer system or the virtual machine, and the second endpoint being one of the host or another virtual machine hosted by the computer system, and the shared memory block including at least one buffer, a post counter, and an acknowledgment counter, wherein sending the data includes:

identifying one of the at least one buffers as being currently owned by the first endpoint and storing data in that buffer;

detecting that the acknowledgment counter is equal to the post counter; and

following detecting that the acknowledgment counter is equal to the post counter, incrementing the post counter to signal that data has been stored for receipt by the second endpoint, and

wherein the medium further stores additional instructions that cause the second endpoint to receive the data from the first endpoint, wherein receiving the data includes;

detecting that the post counter has changed; and

following detecting that the post counter has changed, incrementing the acknowledgment counter to acknowledge receipt of the data.