Abstract: Administering VMs in a distributed computing environment that includes hosts that execute a VMM, with each VMM supporting execution of one or more VMs, includes: assigning the VMMs to a logical tree topology with one as a root; and executing, by the VMMs of the tree topology, a reduce operation, including: sending, by the root VMM to each of other VMMs of the tree topology, a request for an instance of a particular VM; pausing, by each of the other VMMs, the requested instance of the particular VM; providing, by each of the other VMMs to the root VMM in response to the root VMM's request, the requested instance of the particular VM; and identifying, by the root VMM, differences among the requested instances of the particular VM including, performing a bitwise XOR operation amongst the instances of the particular VM.

Abstract: Administering VMs in a distributed computing environment that includes hosts that execute a VMM, with each VMM supporting execution of one or more VMs, includes: assigning the VMMs to a logical tree topology with one as a root; and executing, by the VMMs of the tree topology, a reduce operation, including: sending, by the root VMM to each of other VMMs of the tree topology, a request for an instance of a particular VM; pausing, by each of the other VMMs, the requested instance of the particular VM; providing, by each of the other VMMs to the root VMM in response to the root VMM's request, the requested instance of the particular VM; and identifying, by the root VMM, differences among the requested instances of the particular VM including, performing a bitwise XOR operation amongst the instances of the particular VM.

Abstract: In a distributed computing environment that includes which each execute a VMM, where each VMM supports execution of one or more VMs, administering the VMs may include: assigning, by a VMM manager, the VMMs of the distributed computing environment to a logical tree topology, including assigning one of the VMMs as a root VMM of the tree topology; and executing, amongst the VMMs of the tree topology, a gather operation, including: sending, by the root VMM, to other VMMs in the tree topology, a request to retrieve one or more VMs supported by the other VMMs; pausing, by the other VMMs, each VM requested to be retrieved; and providing, by the other VMMs to the root VMM, the VMs requested to be retrieved.

Abstract: In a distributed computing environment that includes which each execute a VMM, where each VMM supports execution of one or more VMs, administering the VMs may include: assigning, by a VMM manager, the VMMs of the distributed computing environment to a logical tree topology, including assigning one of the VMMs as a root VMM of the tree topology; and executing, amongst the VMMs of the tree topology, a gather operation, including: sending, by the root VMM, to other VMMs in the tree topology, a request to retrieve one or more VMs supported by the other VMMs; pausing, by the other VMMs, each VM requested to be retrieved; and providing, by the other VMMs to the root VMM, the VMs requested to be retrieved.

Abstract: Distributed hardware device simulation, including: identifying a plurality of hardware components of the hardware device; providing software components simulating the functionality of each hardware component, wherein the software components are installed on compute nodes of a distributed processing system; receiving, in at least one of the software components, one or more messages representing an input to the hardware component; simulating the operation of the hardware component with the software component, thereby generating an output of the software component representing the output of the hardware component; and sending, from the software component to at least one other software component, one or more messages representing the output of the hardware component.

Abstract: Managing cooling operations in a parallel computer comprising a plurality of compute nodes, including: receiving, by a target compute node from an origin compute node, a message; identifying, by the target compute node, one or more characteristics of the message; and controlling, by the target compute node, cooling operations in dependence upon the one or more characteristics of the message.

Abstract: Methods, apparatuses, and computer program products for collective operation management in a parallel computer are provided. Embodiments include a parallel computer having a first compute node operatively coupled for data communications over a tree data communications network with a plurality of child compute nodes. Embodiments also include each child compute node performing a first collective operation. The first compute rode, for each child compute node, receives from the child compute node, a result of the first collective operation performed by the child compute node. For each result received from a child compute node, the first compute node stores a timestamp indicating a time that the child compute node completed the first collective operation. The first compute node also manages, based on the stored timestamps, execution of a second collective operation over the tree data communications network.

Abstract: Routing data communications packets in a parallel computer that includes compute nodes organized for collective operations. Each compute node including an operating system kernel and a system-level messaging module that is a module of automated computing machinery that exposes a messaging interface to applications. Each compute node including a routing table that specifies, for each of a multiplicity of route identifiers, a data communications path through the compute node. Including to carry out the steps of: receiving in a compute node a data communications packet that includes a route identifier value; retrieving from the routing table a specification of a data communications path through the compute node; and routing, by the compute node, the data communications packet according to the data communications path identified by the compute node's routing table entry for the data communications packet's route identifier value.

Abstract: Routing data communications packets in a parallel computer that includes compute nodes organized for collective operations. Each compute node including an operating system kernel and a system-level messaging module that is a module of automated computing machinery that exposes a messaging interface to applications. Each compute node including a routing table that specifies, for each of a multiplicity of route identifiers, a data communications path through the compute node. Including to carry out the steps of: receiving in a compute node a data communications packet that includes a route identifier value; retrieving from the routing table a specification of a data communications path through the compute node; and routing, by the compute node, the data communications packet according to the data communications path identified by the compute node's routing table entry for the data communications packet's route identifier value.

Abstract: Data communications may be carried out in a distributed computing environment that includes a plurality of computers coupled for data communications through communications adapters and an active messaging interface (‘AMI’). In such an environment, data communications may include: issuing, by a sender to a receiver, an eager SEND data communications instruction to transfer SEND data, the instruction including information describing a location and size of a send buffer in which the SEND data is stored; transmitting, by the sender to the receiver, the SEND data as eager data packets; issuing, by the receiver to the sender in dependence upon data flow conditions, a STOP instruction, the STOP instruction including an order to stop transmitting the eager data packets; and transferring the SEND data by the receiver from the sender's data location to a receive buffer by remote direct memory access (“RDMA”).

Abstract: Methods, parallel computers, and computer program products for requesting shared variable directory (SVD) information from a plurality of threads in a parallel computer are provided. Embodiments include a runtime optimizer detecting that a first thread requires a plurality of updated SVD information associated with shared resource data stored in a plurality of memory partitions. Embodiments also include a runtime optimizer broadcasting, in response to detecting that the first thread requires the updated SVD information, a gather operation message header to the plurality of threads. The gather operation message header indicates an SVD key corresponding to the required updated SVD information and a local address associated with the first thread to receive a plurality of updated SVD information associated with the SVD key. Embodiments also include the runtime optimizer receiving at the local address, the plurality of updated SVD information from the plurality of threads.

Abstract: Methods, parallel computers, and computer program products for requesting shared variable directory (SVD) information from a plurality of threads in a parallel computer are provided. Embodiments include a runtime optimizer detecting that a first thread requires a plurality of updated SVD information associated with shared resource data stored in a plurality of memory partitions. Embodiments also include a runtime optimizer broadcasting, in response to detecting that the first thread requires the updated SVD information, a gather operation message header to the plurality of threads. The gather operation message header indicates an SVD key corresponding to the required updated SVD information and a local address associated with the first thread to receive a plurality of updated SVD information associated with the SVD key. Embodiments also include the runtime optimizer receiving at the local address, the plurality of updated SVD information from the plurality of threads.

Abstract: Adjusting environmental variables in an adaptive parameter adjustment runtime environment, including: executing a parallel program by the adaptive parameter adjustment runtime environment, including beginning operations with a set of default global parameter values; maintaining a list of configurable parameters; changing a parameter value for a parameter in the list of configurable parameters; determining whether an effect of changing the parameter value is positive, negative, or neutral; responsive to determining that the effect of changing the parameter value is positive, changing the parameter value for the parameter; responsive to determining that the effect of changing the parameter value is negative, changing the parameter value for the parameter to a previous value; and responsive to determining that the effect of changing the parameter value is neutral, performing a list management operation on the list of configurable parameters.

Abstract: In a distributed computing environment that includes hosts that execute a VMM, where each VMM supports execution of one or more VMs, administering VMs may include: assigning, by a VMM manager, the VMMs of the distributed computing environment to a logical tree topology, including assigning one of the VMMs as a root VMM of the tree topology; and executing, amongst the VMMs of the tree topology, a broadcast operation, including: pausing, by the root VMM, execution of one or more VMs supported by the root VMM; sending, by the root VMM, to other VMMs in the tree topology, a message indicating a pending transfer of the paused VMs; and transferring the paused VMs from the root VMM to the other VMMs.

Abstract: Developing collective operations for a parallel computer that includes compute nodes includes: presenting, by a collective development tool, a graphical user interface (‘GUI’) to a collective developer; receiving, by the collective development tool from the collective developer through the GUI, a selection of one or more collective primitives; receiving, by the collective development tool from the collective developer through the GUI, a specification of a serial order of the collective primitives and a specification of input and output buffers for each collective primitive; and generating, by the collective development tool in dependence upon the selection of collective primitives, the serial order of the collective primitives, and the input and output buffers for each collective primitive, executable code that carries out the collective operation specified by the collective primitives.

Abstract: In a distributed computing environment that includes hosts which each execute a VMM, with each VMM supporting execution of one or more VMs, administering a the VMs may include: assigning, by a VMM manager, the VMMs of the distributed computing environment to a logical tree topology, including assigning one of the VMMs as a root VMM of the tree topology; and executing, amongst the VMMs of the tree topology, an allgather operation, including: sending, by the root VMM, to other VMMs in the tree topology, a request to retrieve VMs supported by the other VMMs; pausing, by each of the other VMMs, a VM supported by the VMM; providing, by each of the other VMMs as a response to the root VMM's request, the paused VM; and broadcasting, by the root VM to the other VMMs as a set of VMs, the received VMs.

Abstract: Constructing a logical tree topology in a parallel computer that includes compute nodes, where each compute node includes a hardware acceleration unit and executes an identical number of tasks and the tasks of each node have a rank, includes: creating hardware acceleration groups, with each hardware acceleration group including one task from each node, where the one task from each node has the same rank; assigning one task of a root compute node as a global root of the logical tree topology; assigning tasks of the root compute node other than the global root as local children of the global root; and assigning each of the global root and local children of the root compute node as a root of a subtree of tasks, wherein each subtree comprises the tasks of a hardware acceleration group.

Abstract: Developing collective operations for a parallel computer that includes compute nodes includes: presenting, by a collective development tool, a graphical user interface (‘GUI’) to a collective developer; receiving, by the collective development tool from the collective developer through the GUI, a selection of one or more collective primitives; receiving, by the collective development tool from the collective developer through the GUI, a specification of a serial order of the collective primitives and a specification of input and output buffers for each collective primitive; and generating, by the collective development tool in dependence upon the selection of collective primitives, the serial order of the collective primitives, and the input and output buffers for each collective primitive, executable code that carries out the collective operation specified by the collective primitives.

Abstract: Constructing a logical tree topology in a parallel computer that includes compute nodes, where each compute node includes a hardware acceleration unit and executes an identical number of tasks and the tasks of each node have a rank, includes: creating hardware acceleration groups, with each hardware acceleration group including one task from each node, where the one task from each node has the same rank; assigning one task of a root compute node as a global root of the logical tree topology; assigning tasks of the root compute node other than the global root as local children of the global root; and assigning each of the global root and local children of the root compute node as a root of a subtree of tasks, wherein each subtree comprises the tasks of a hardware acceleration group.

Abstract: Administering group identifiers of processes in a parallel computer includes each process in a set of processes, receiving from a compute node of the plurality of compute nodes, a request to establish the set of processes as an operational group including receiving a list of process identifiers for each process of the set of processes. Embodiments also include each process generating without communication amongst the processes, a unique group identifier in dependence upon the list of process identifiers.