Abstract: Methods, systems, and products are disclosed for data transfers between nodes in a parallel computer that include: receiving, by an origin DMA on an origin node, a buffer identifier for a buffer containing data for transfer to a target node; sending, by the origin DMA to the target node, a RTS message; transferring, by the origin DMA, a data portion to the target node using a memory FIFO operation that specifies one end of the buffer from which to begin transferring the data; receiving, by the origin DMA, an acknowledgement of the RTS message from the target node; and transferring, by the origin DMA in response to receiving the acknowledgement, any remaining data portion to the target node using a direct put operation that specifies the other end of the buffer from which to begin transferring the data, including initiating the direct put operation without invoking an origin processing core.

Abstract: A parallel computer including compute nodes, each including two reduction processing cores, a network write processing core, and a network read processing core, each processing core assigned an input buffer. Copying, in interleaved chunks by the reduction processing cores, contents of the reduction processing cores' input buffers to an interleaved buffer in shared memory; copying, by one of the reduction processing cores, contents of the network write processing core's input buffer to shared memory; copying, by another of the reduction processing cores, contents of the network read processing core's input buffer to shared memory; and locally reducing in parallel by the reduction processing cores: the contents of the reduction processing core's input buffer; every other interleaved chunk of the interleaved buffer; the copied contents of the network write processing core's input buffer; and the copied contents of the network read processing core's input buffer.

Abstract: Methods, apparatus, and products are disclosed for thread selection during context switching on a plurality of compute nodes that includes: executing, by a compute node, an application using a plurality of threads of execution, including executing one or more of the threads of execution; selecting, by the compute node from a plurality of available threads of execution for the application, a next thread of execution in dependence upon power characteristics for each of the available threads; determining, by the compute node, whether criteria for a thread context switch are satisfied; and performing, by the compute node, the thread context switch if the criteria for a thread context switch are satisfied, including executing the next thread of execution.

Abstract: Compute nodes of a parallel computer organized for collective operations via a network, each compute node having a receive buffer and establishing a topology for the network; selecting a schedule for a broadcast operation; depositing, by a root node of the topology, broadcast data in a target node's receive buffer, including performing a DMA operation with a well-known memory location for the target node's receive buffer; depositing, by the root node in a memory region designated for storing broadcast data length, a length of the broadcast data, including performing a DMA operation with a well-known memory location of the broadcast data length memory region; and triggering, by the root node, the target node to perform a next DMA operation, including depositing, in a memory region designated for receiving injection instructions for the target node, an instruction to inject the broadcast data into the receive buffer of a subsequent target node.

Abstract: Paging memory from random access memory (‘RAM’) to backing storage in a parallel computer that includes a plurality of compute nodes, including: executing a data processing application on a virtual machine operating system in a virtual machine on a first compute node; providing, by a second compute node, backing storage for the contents of RAM on the first compute node; and swapping, by the virtual machine operating system in the virtual machine on the first compute node, a page of memory from RAM on the first compute node to the backing storage on the second compute node.

Abstract: Internode data communications in a parallel computer that includes compute nodes that each include main memory and a messaging unit, the messaging unit including computer memory and coupling compute nodes for data communications, in which, for each compute node at compute node boot time: a messaging unit allocates, in the messaging unit's computer memory, a predefined number of message buffers, each message buffer associated with a process to be initialized on the compute node; receives, prior to initialization of a particular process on the compute node, a data communications message intended for the particular process; and stores the data communications message in the message buffer associated with the particular process. Upon initialization of the particular process, the process establishes a messaging buffer in main memory of the compute node and copies the data communications message from the message buffer of the messaging unit into the message buffer of main memory.

Abstract: Intranode data communications in a parallel computer that includes compute nodes configured to execute processes, where the data communications include: allocating, upon initialization of a first process of a compute node, a region of shared memory; establishing, by the first process, a predefined number of message buffers, each message buffer associated with a process to be initialized on the compute node; sending, to a second process on the same compute node, a data communications message without determining whether the second process has been initialized, including storing the data communications message in the message buffer of the second process; and upon initialization of the second process: retrieving, by the second process, a pointer to the second process's message buffer; and retrieving, by the second process from the second process's message buffer in dependence upon the pointer, the data communications message sent by the first process.

Abstract: A parallel computer includes nodes, each having main memory and a messaging unit (MU). Each MU includes computer memory, which in turn includes, MU message buffers. Each MU message buffer is associated with an uninitialized process on the compute node. In the parallel computer, managing internode data communications for an uninitialized process includes: receiving, by an MU of a compute node, one or more data communications messages in an MU message buffer associated with an uninitialized process on the compute node; determining, by an application agent, that the MU message buffer associated with the uninitialized process is full prior to initialization of the uninitialized process; establishing, by the application agent, a temporary message buffer for the uninitialized process in main computer memory; and moving, by the application agent, data communications messages from the MU message buffer associated with the uninitialized process to the temporary message buffer in main computer memory.

Abstract: Graphics based IDE for distributed computing systems software development including providing a graphical representation of a topology of a distributed computing system for which the user is to develop a software application; receiving an identification of a system component upon which a portion of the application is to execute; providing a text editor for receiving from the user computer program instructions forming the portion of the application; inserting, without user intervention as part of the portion of the application, predetermined computer program instructions configured to support the identified system component; receiving, through the text editor, the portion of the application including the predetermined computer program instructions configured to support the identified system component; and storing, the computer program instructions forming the portion of the application, at a user specified location within the application.

Abstract: A parallel computer executes a number of tasks, each task includes a number of endpoints and the endpoints are configured to support collective operations. In such a parallel computer, establishing a group of endpoints receiving a user specification of a set of endpoints included in a global collection of endpoints, where the user specification defines the set in accordance with a predefined virtual representation of the endpoints, the predefined virtual representation is a data structure setting forth an organization of tasks and endpoints included in the global collection of endpoints and the user specification defines the set of endpoints without a user specification of a particular endpoint; and defining a group of endpoints in dependence upon the predefined virtual representation of the endpoints and the user specification.

Abstract: Performing a local barrier operation with parallel tasks executing on a compute node including, for each task: retrieving a present value of a counter; calculating, in dependence upon the present value of the counter and a total number of tasks performing the local barrier operation, a base value of the counter, the base value representing the counter's value prior to any task joining the local barrier; calculating, in dependence upon the base value and the total number of tasks performing the local barrier operation, a target value of the counter, the target value representing the counter's value when all tasks have joined the local barrier; joining the local barrier, including atomically incrementing the value of the counter; and repetitively, until the present value of the counter is no less than the target value of the counter: retrieving the present value of the counter and determining whether the present value equals the target value.

Abstract: Collective operation protocol selection in a parallel computer that includes compute nodes may be carried out by calling a collective operation with operating parameters; selecting a protocol for executing the operation and executing the operation with the selected protocol. Selecting a protocol includes: iteratively, until a prospective protocol meets predetermined performance criteria: providing, to a protocol performance function for the prospective protocol, the operating parameters; determining whether the prospective protocol meets predefined performance criteria by evaluating a predefined performance fit equation, calculating a measure of performance of the protocol for the operating parameters; determining that the prospective protocol meets predetermined performance criteria and selecting the protocol for executing the operation only if the calculated measure of performance is greater than a predefined minimum performance threshold.

Abstract: Performing a global barrier operation in a parallel computer that includes compute nodes coupled for data communications, where each compute node executes tasks, with one task on each compute node designated as a master task, including: for each task on each compute node until all master tasks have joined a global barrier: determining whether the task is a master task; if the task is not a master task, joining a single local barrier; if the task is a master task, joining the global barrier and the single local barrier only after all other tasks on the compute node have joined the single local barrier.

Abstract: Methods, apparatus, and products are disclosed for budget-based power consumption for application execution on a plurality of compute nodes that include: assigning an execution priority to each of one or more applications; executing, on the plurality of compute nodes, the applications according to the execution priorities assigned to the applications at an initial power level provided to the compute nodes until a predetermined power consumption threshold is reached; and applying, upon reaching the predetermined power consumption threshold, one or more power conservation actions to reduce power consumption of the plurality of compute nodes during execution of the applications.

Abstract: Methods, systems, and products are disclosed for administering an epoch initiated for remote memory access that include: initiating, by an origin application messaging module on an origin compute node, one or more data transfers to a target compute node for the epoch; initiating, by the origin application messaging module after initiating the data transfers, a closing stage for the epoch, including rejecting any new data transfers after initiating the closing stage for the epoch; determining, by the origin application messaging module, whether the data transfers have completed; and closing, by the origin application messaging module, the epoch if the data transfers have completed.

Abstract: Compute nodes of a parallel computer organized for collective operations via a network, each compute node having a receive buffer and establishing a topology for the network; selecting a schedule for a broadcast operation; depositing, by a root node of the topology, broadcast data in a target node's receive buffer, including performing a DMA operation with a well-known memory location for the target node's receive buffer; depositing, by the root node in a memory region designated for storing broadcast data length, a length of the broadcast data, including performing a DMA operation with a well-known memory location of the broadcast data length memory region; and triggering, by the root node, the target node to perform a next DMA operation, including depositing, in a memory region designated for receiving injection instructions for the target node, an instruction to inject the broadcast data into the receive buffer of a subsequent target node.

Abstract: A parallel computer including compute nodes, each including two reduction processing cores, a network write processing core, and a network read processing core, each processing core assigned an input buffer. Copying, in interleaved chunks by the reduction processing cores, contents of the reduction processing cores' input buffers to an interleaved buffer in shared memory; copying, by one of the reduction processing cores, contents of the network write processing core's input buffer to shared memory; copying, by another of the reduction processing cores, contents of the network read processing core's input buffer to shared memory; and locally reducing in parallel by the reduction processing cores: the contents of the reduction processing core's input buffer; every other interleaved chunk of the interleaved buffer; the copied contents of the network write processing core's input buffer; and the copied contents of the network read processing core's input buffer.

Abstract: A parallel computer including compute nodes, each including two reduction processing cores, a network write processing core, and a network read processing core, each processing core assigned an input buffer. Copying, in interleaved chunks by the reduction processing cores, contents of the reduction processing cores' input buffers to an interleaved buffer in shared memory; copying, by one of the reduction processing cores, contents of the network write processing core's input buffer to shared memory; copying, by another of the reduction processing cores, contents of the network read processing core's input buffer to shared memory; and locally reducing in parallel by the reduction processing cores: the contents of the reduction processing core's input buffer; every other interleaved chunk of the interleaved buffer; the copied contents of the network write processing core's input buffer; and the copied contents of the network read processing core's input buffer.

Abstract: Methods, parallel computers, and computer program products are disclosed for remote direct memory access.

Abstract: Methods, apparatus, and products are disclosed for scheduling applications for execution on a plurality of compute nodes of a parallel computer to manage temperature of the plurality of compute nodes during execution that include: identifying one or more applications for execution on the plurality of compute nodes; creating a plurality of physically discontiguous node partitions in dependence upon temperature characteristics for the compute nodes and a physical topology for the compute nodes, each discontiguous node partition specifying a collection of physically adjacent compute nodes; and assigning, for each application, that application to one or more of the discontiguous node partitions for execution on the compute nodes specified by the assigned discontiguous node partitions.