Configurable I/O address translation data structure

A program product for configuring an input/output (I/O) address translation data structure in a data processing system, the program product comprising:

• a computer-readable storage device;
• and
• program code stored within the computer-readable storage device, wherein the program code, when executed by a computer, causes the computer to perform:
• in response to determining to allocate additional storage, within a real address space employed by a system memory of a data processing system, for translation control entries (TCEs) that translate addresses from an input/output (I/O) address space to the real address space, determining whether or not a first real address range contiguous with an existing TCE data structure in the system memory is currently unallocated and available for allocation;
• in response to determining that the first real address range is currently unallocated and available for allocation, allocating the first real address range for storage of the TCEs and retaining a first number of levels in the existing TCE data structure;
• in response to determining that the first real address range is not currently unallocated and available for allocation:
• determining whether or not to move a data set from the first real address range based on at least one input in a set consisting of (1) a priority of a logical partition of a partitionable endpoint in the I/O subsystem for which addresses are translated by reference to the TCE data structure, (2) a type of workload of the logical partition, (3) a priority of a process utilizing the partitionable endpoint, and (4) a utilization percentage of the partitionable endpoint;
• in response to determining to move the data set, moving the data set from the first real address range to a third real address range, allocating the first real address range for storage of the TCEs, and retaining the first number of levels in the existing TCE data structure;
• and
• in response to determining not to move the data set, allocating storage for the TCEs in a second real address range discontiguous with the existing TCE data structure and increasing the number of levels in the TCE data structure from the first number to a greater second number.

A method of configuring an input/output (I/O) address translation data structure in a data processing system, the method comprising:

• in response to determining to allocate additional storage, within a real address space employed by a system memory of a data processing system, for translation control entries (TCEs) that translate addresses from an input/output (I/O) address space to the real address space, a processor of the data processing system determining whether or not a first real address range contiguous with an existing TCE data structure in the system memory is currently unallocated and available for allocation, wherein the existing TCE data structure has a first number of levels;
• based on a determination that the first real address range is not currently unallocated and available for allocation, the processor:
• determining whether or not to move a data set from the first real address range based on at least one input in a set consisting of (1) a priority of a logical partition of a partitionable endpoint in the I/O subsystem for which addresses are translated by reference to the TCE data structure, (2) a type of workload of the logical partition, (3) a priority of a process utilizing the partitionable endpoint, and (4) a utilization percentage of the partitionable endpoint;
• based on a determination to move the data set, moving the data set from the first real address range to a third real address range, allocating the first real address range for storage of the TCEs, and retaining the first number of levels in the existing TCE data structure;
• and
• based on a determination not to move the data set, allocating storage for the TCEs in a second real address range discontiguous with the existing TCE data structure and increasing the number of levels in the TCE data structure from the first number to a greater second number.