Abstract: An example computer-implemented method may include receiving, by a general purpose processor, the I/O operation. The method may further include transmitting, by the general purpose processor, the I/O operation to a system assist processor. The method may further include transmitting, by the system assist processor, the I/O operation to an I/O channel for execution by the I/O channel, wherein transmitting the I/O operation to the I/O channel comprises queuing the I/O operation in the multi-queue. The method may further include executing, by the I/O channel, the I/O operation.

Abstract: Examples of techniques for processing I/O operations in a channel are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method may include: copying, by a system assist processor, a subchannel of the channel into a lower portion of a channel communication area responsive to receiving the I/O operation; copying, by the system assist processor, channel program information from a designated starting location in a customer memory into a control block; building, by the system assist processor, a starting channel communication area into a top portion of the control block; queuing, by the system assist processor, the control block to a queue for the channel; processing, by the channel, the I/O operation responsive to retrieving the control block from the queue.

Abstract: Examples of techniques for queuing an input/output (I/O) operation in a multi-queue are disclosed. In one example implementation according to aspects of the present disclosure, an example computer-implemented method may include receiving, by a general purpose processor, the I/O operation. The method may further include transmitting, by the general purpose processor, the I/O operation to a system assist processor. The method may further include transmitting, by the system assist processor, the I/O operation to an I/O channel for execution by the I/O channel, wherein transmitting the I/O operation to the I/O channel comprises queuing the I/O operation in the multi-queue. The method may further include executing, by the I/O channel, the I/O operation.

Abstract: Examples of techniques for processing I/O operations in a channel are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method may include: copying, by a system assist processor, a subchannel of the channel into a lower portion of a channel communication area responsive to receiving the I/O operation; copying, by the system assist processor, channel program information from a designated starting location in a customer memory into a control block; building, by the system assist processor, a starting channel communication area into a top portion of the control block; queuing, by the system assist processor, the control block to a queue for the channel; processing, by the channel, the I/O operation responsive to retrieving the control block from the queue.

Abstract: Examples of techniques for processing I/O operations in a channel are disclosed. In one example implementation according to aspects of the present disclosure, a computer-implemented method may include: copying, by a system assist processor, a subchannel of the channel into a lower portion of a channel communication area responsive to receiving the I/O operation; copying, by the system assist processor, channel program information from a designated starting location in a customer memory into a control block; building, by the system assist processor, a starting channel communication area into a top portion of the control block; queuing, by the system assist processor, the control block to a queue for the channel; processing, by the channel, the I/O operation responsive to retrieving the control block from the queue.

Abstract: A method for implementing connected input/output (I/O) hub configuration and management includes configuring a first I/O hub in wrap mode with a second I/O hub. The hubs are communicatively coupled via a wrap cable. The method further includes generating data traffic on a computing subsystem that includes the hubs. Generating traffic includes: converting, via the first hub, a request to implement a transaction into an I/O device-readable request packet and transmitting the request packet over the wrap cable; converting, via the second hub, the I/O device-readable (IODR) request packet into a system readable request and transmitting the request over a system bus; converting, via the second hub, the response to an IODR response packet, and transmitting the response packet over the wrap cable; and converting, via the first hub, the IODR response packet into a system readable response packet, and transmitting the response packet over the system bus.

Abstract: A system and a method for failover control comprising: maintaining a primary device table entry (DTE) in a first table activated for a first adapter in communication with a first processor node having a first root complex via a first switch assembly and maintaining a secondary DTE in standby for a second adapter in communication with a second processor node having a second root complex via a second switch assembly; maintaining a primary DTE in a second table activated for the second adapter and maintaining a secondary DTE in standby for the first adapter; and upon a failover, updating the secondary DTE in the first table as an active entry for the second adapter and forming a path to enable traffic to route from the second adapter through the second switch assembly over to the first switch assembly and up to the first root complex of the first processor node.

Abstract: A system for implementing non-standard I/O adapters in a standardized I/O architecture, the system comprising an I/O hub communicatively coupled to an I/O bus and at least one I/O adapter, the I/O hub including logic for implementing a method, the method comprising receiving a request to perform an operation on the I/O adapter from a requester at a requester address, the I/O adapter at a destination address, determining that the request is in a format other than a format supported by the I/O bus, the I/O bus expecting a requester identifier at a first location in a header of the request, reformatting the request into the format supported by the I/O bus, the reformatting comprising storing the requester address, the destination address and an operation code at the first location in the header of the reformatted request, and sending the reformatted request to the I/O adapter.

Abstract: A method for implementing connected input/output (I/O) hub configuration and management includes configuring a first I/O hub in wrap mode with a second I/O hub. The hubs are communicatively coupled via a wrap cable. The method further includes generating data traffic on a computing subsystem that includes the hubs. Generating traffic includes: converting, via the first hub, a request to implement a transaction into an I/O device-readable request packet and transmitting the request packet over the wrap cable; converting, via the second hub, the I/O device-readable (IODR) request packet into a system readable request and transmitting the request over a system bus; converting, via the second hub, the response to an IODR response packet, and transmitting the response packet over the wrap cable; and converting, via the first hub, the IODR response packet into a system readable response packet, and transmitting the response packet over the system bus.

Abstract: A configuration adaptation layer (CAL) for I/O devices such as I/O adapters is provided. This configuration adaptation layer (CAL) explicitly provides a mapping between adapter functions and adapter resources in a way such that it is senseable in-band by the computer system using the adapter, e.g., by a virtual machine monitor.

Abstract: A method for implementing connected input/output (I/O) hub configuration and management includes configuring a first I/O hub in wrap mode with a second I/O hub. The hubs are communicatively coupled via a wrap cable. The method further includes generating data traffic on a computing subsystem that includes the hubs. Generating traffic includes: converting, via the first hub, a request to implement a transaction into an I/O device-readable request packet and transmitting the request packet over the wrap cable; converting, via the second hub, the I/O device-readable (IODR) request packet into a system readable request and transmitting the request over a system bus; converting, via the second hub, the response to an IODR response packet, and transmitting the response packet over the wrap cable; and converting, via the first hub, the IODR response packet into a system readable response packet, and transmitting the response packet over the system bus.

Abstract: A system for implementing non-standard I/O adapters in a standardized I/O architecture, the system comprising an I/O hub communicatively coupled to an I/O bus and at least one I/O adapter, the I/O hub including logic for implementing a method, the method comprising receiving a request to perform an operation on the I/O adapter from a requester at a requester address, the I/O adapter at a destination address, determining that the request is in a format other than a format supported by the I/O bus, the I/O bus expecting a requester identifier at a first location in a header of the request, reformatting the request into the format supported by the I/O bus, the reformatting comprising storing the requester address, the destination address and an operation code at the first location in the header of the reformatted request, and sending the reformatted request to the I/O adapter.

Abstract: A system and a method for failover control comprising: maintaining a primary device table entry (DTE) in a first table activated for a first adapter in communication with a first processor node having a first root complex via a first switch assembly and maintaining a secondary DTE in standby for a second adapter in communication with a second processor node having a second root complex via a second switch assembly; maintaining a primary DTE in a second table activated for the second adapter and maintaining a secondary DTE in standby for the first adapter; and upon a failover, updating the secondary DTE in the first table as an active entry for the second adapter and forming a path to enable traffic to route from the second adapter through the second switch assembly over to the first switch assembly and up to the first root complex of the first processor node.

Abstract: A balancing process between I/O processor groups of a non-uniform multi-processor system enables spreading of I/O workload across multiple I/O processor groups on a group base as soon as the I/O processor group with maximum group utilization reaches a certain high limit together with other processor groups being utilized significantly lower. The additional balancing is decreased step by step again when a certain low utilization limit is reached or the workload becomes more evenly balanced between the I/O processor groups. Checking if increase or decrease of the balancing is required is done periodically, but with low frequency to not affect overall performance. The checking and balancing happens asynchronously in predefined intervals. This solves the problem that with an increasing number of I/O processors the handling of initiatives leads to increased cache traffic and contention due to shared data structures, which slows down the I/O workload handling significantly.

Abstract: A configuration adaptation layer (CAL) for I/O devices such as I/O adapters is provided. This configuration adaptation layer (CAL) explicitly provides a mapping between adapter functions and adapter resources in a way such that it is senseable in-band by the computer system using the adapter, e.g., by a virtual machine monitor.