High-speed packet transfer in computer systems with multiple interfaces

A method for transferring a data set between a virtual machine and a target via a virtual machine monitor, a host interface, and a channel, where:

• the virtual machine follows a transfer protocol in which the data set is transferred as a series of packets, and transfer of at least one subsequent packet is contingent on completed transfer of at least one previous packet;
• data transfer between the virtual machine and the host interface takes place via the virtual machine monitor;
• the host interface initiates data transfer via the channel upon receipt of a transfer request and of identification of the data set to be transferred, and of identification of the target;
• the method comprising:
• within the virtual machine monitor,
• A) receiving a first one of the packets from the virtual machine;
• B) signaling to the virtual machine that the transfer of the first packet is still pending, so that the virtual machine at least temporarily delays submission of subsequent packets to the virtual machine monitor;
• C) issuing to the host interface a transfer request and identifying for the host interface the data set to be transferred, whereupon the host interface attempts transfer of the data set;
• D) upon sensing a completion signal from the host interface indicating completed transfer of the data set,
• i) signaling to the virtual machine completed transfer of the first packet;
• ii) receiving subsequent packets from the virtual machine and, for each, signaling to the virtual machine completed transfer of each subsequent packet.

A method for transferring a data set from a transfer-initiating subsystem to a target via an intermediate subsystem, a transfer-executing subsystem, and a channel, where:

• A) the transfer-initiating subsystem
• i) stores the data set in a memory space accessible to the intermediate subsystem;
• ii) derives, for the data set stored in the memory space, a plurality of descriptors, each descriptor specifying at least a memory location of a corresponding sub-set of the data set;
• iii) follows a transfer protocol in which the data set is transferred as a series of packets;
• iv) generates the packets at least partially based on the descriptors;
• and
• v) transfers at least one subsequent packet contingent on completed transfer of at least one previous packet;
• B) data transfer from the transfer-initiating subsystem to the transfer-executing subsystem takes place via the intermediate subsystem;
• C) the transfer-executing subsystem initiates data transfer via the channel upon receipt of a transfer request and of identification of the data set to be transferred;
• the method comprising:
• D) within the intermediate subsystem,
• i) creating, independently of action by the transfer-initiating subsystem, a copy of the data set by evaluating the descriptors and by accessing the memory space in which the transfer-initiating subsystem has stored the data set;
• and
• ii) identifying for the transfer-executing subsystem the copy of the data set as the data set to be transferred and issuing the transfer request to the transfer-executing subsystem;
• iii) receiving a first one of the packets from the transfer-initiating subsystem;
• iv) signaling to the transfer-initiating subsystem that the transfer of the first packet is still pending, so that the transfer-initiating subsystem at least temporarily delays submission of subsequent packets to the intermediate subsystem;
• v) issuing to the transfer-executing subsystem a transfer request and identifying for the transfer-executing subsystem the data set to be transferred, whereupon the transfer-executing subsystem attempts transfer of the data set to the target;
• and
• vi) upon sensing a completion signal from the transfer-executing subsystem indicating completed transfer of the data set,
• a) signaling to the transfer-initiating subsystem completed transfer of the first packet;
• and
• b) receiving subsequent packets from the transfer-initiating subsystem and, for each, signaling to the transfer-initiating subsystem completed transfer of each subsequent packet.

A system for transferring a data set between a transfer-initiating subsystem and a target via a transfer-executing subsystem and over a channel, where:

• A) the transfer-initiating subsystem follows a transfer protocol in which the data set is transferred as a series of packets, and transfer of at least one subsequent packet is contingent on completed transfer of at least one previous packet;
• B) the transfer-executing subsystem initiates data transfer via the channel upon receipt of a transfer request and of identification of the data set to be transferred;
• the system comprising:
• C) an intermediate subsystem
• i) forming an interface between the transfer-initiating subsystem and the transfer-executing subsystem,
• ii) forming means for identifying for the transfer-executing subsystem the data set to be transferred, whereupon the transfer-executing subsystem attempts transfer of the data set;
• iii) and including:
• a) an emulated channel forming means for receiving the packets from the transfer-initiating subsystem and for signaling to the transfer-initiating subsystem that the transfer of a first packet is still pending, so that the transfer-initiating subsystem at least temporarily delays submission of subsequent packets to the intermediate subsystem;
• b) transfer management means for issuing to the transfer-executing subsystem a transfer request and for receiving a completion signal from the transfer-executing subsystem indicating completed transfer of the data set;
• D) the emulated channel being further provided, upon receipt by the transfer management means of the completion signal,
• i) for signaling to the transfer-initiating subsystem completed transfer of the first packet;
• and
• ii) for receiving subsequent packets from the transfer-initiating subsystem and, for each, for signaling to the transfer-initiating subsystem completed transfer of each subsequent packet.