Abstract: Synchronizing time bases in a parallel computer that includes compute nodes organized for data communications in a tree network, where one compute node is designated as a root, and, for each compute node: calculating data transmission latency from the root to the compute node; configuring a thread as a pulse waiter; initializing a wakeup unit; and performing a local barrier operation; upon each node completing the local barrier operation, entering, by all compute nodes, a global barrier operation; upon all nodes entering the global barrier operation, sending, to all the compute nodes, a pulse signal; and for each compute node upon receiving the pulse signal: waking, by the wakeup unit, the pulse waiter; setting a time base for the compute node equal to the data transmission latency between the root node and the compute node; and exiting the global barrier operation.

Abstract: Synchronizing time bases in a parallel computer that includes compute nodes organized for data communications in a tree network, where one compute node is designated as a root, and, for each compute node: calculating data transmission latency from the root to the compute node; configuring a thread as a pulse waiter; initializing a wakeup unit; and performing a local barrier operation; upon each node completing the local barrier operation, entering, by all compute nodes, a global barrier operation; upon all nodes entering the global barrier operation, sending, to all the compute nodes, a pulse signal; and for each compute node upon receiving the pulse signal: waking, by the wakeup unit, the pulse waiter; setting a time base for the compute node equal to the data transmission latency between the root node and the compute node; and exiting the global barrier operation.

Abstract: Calculating a checksum utilizing inactive networking components in a computing system, including: identifying, by a checksum distribution manager, an inactive networking component, wherein the inactive networking component includes a checksum calculation engine for computing a checksum; sending, to the inactive networking component by the checksum distribution manager, metadata describing a block of data to be transmitted by an active networking component; calculating, by the inactive networking component, a checksum for the block of data; transmitting, to the checksum distribution manager from the inactive networking component, the checksum for the block of data; and sending, by the active networking component, a data communications message that includes the block of data and the checksum for the block of data.

Abstract: Techniques are described for using geographic location data of snowplows to update a snow depth associated with a section of a surface street. The route of the snowplow may be tracked continuously which allows the snow depth of the street to be reset in real-time. The updated snow depth may then be used to generate a cost of travelling on the street. The travelling cost may then be used to plan a route through the region. Alternatively, the cost may be graphically displayed on a map to permit a user to determine which surface streets to avoid. In another embodiment, the cost of travelling on a particular street may be changed by the attributes of the vehicle that will navigate the snow-covered roads, driver's experience, or the geographic terrain of a road. This new cost may then be used, for example, to plan a route or display roads to avoid.

Abstract: In an embodiment, if a self thread has more than one conflict, a transaction of the self thread is aborted and restarted. If the self thread has only one conflict and an enemy thread of the self thread has more than one conflict, the transaction of the self thread is committed. If the self thread only conflicts with the enemy thread and the enemy thread only conflicts with the self thread and the self thread has a key that has a higher priority than a key of the enemy thread, the transaction of the self thread is committed. If the self thread only conflicts with the enemy thread, the enemy thread only conflicts with the self thread, and the self thread has a key that has a lower priority than the key of the enemy thread, the transaction of the self thread is aborted.

Abstract: Techniques are described for using geographic location data of snowplows to update a snow depth associated with a section of a surface street. The route of the snowplow may be tracked continuously which allows the snow depth of the street to be reset in real-time. The updated snow depth may then be used to generate a cost of travelling on the street. The travelling cost may then be used to plan a route through the region. Alternatively, the cost may be graphically displayed on a map to permit a user to determine which surface streets to avoid. In another embodiment, the cost of travelling on a particular street may be changed by the attributes of the vehicle that will navigate the snow-covered roads, driver's experience, or the geographic terrain of a road. This new cost may then be used, for example, to plan a route or display roads to avoid.

Abstract: Remote direct memory access (‘RDMA’) in a parallel computer, the parallel computer including a plurality of nodes, each node including a messaging unit, including: receiving an RDMA read operation request that includes a virtual address representing a memory region at which to receive data to be transferred from a second node to the first node; responsive to the RDMA read operation request: translating the virtual address to a physical address; creating a local RDMA object that includes a counter set to the size of the memory region; sending a message that includes an DMA write operation request, the physical address of the memory region on the first node, the physical address of the local RDMA object on the first node, and a remote virtual address on the second node; and receiving the data to be transferred from the second node.

Abstract: Techniques are disclosed for loading programs efficiently in a parallel computing system. In one embodiment, nodes of the parallel computing system receive a load description file which indicates, for each program of a multiple program multiple data (MPMD) job, nodes which are to load the program. The nodes determine, using collective operations, a total number of programs to load and a number of programs to load in parallel. The nodes further generate a class route for each program to be loaded in parallel, where the class route generated for a particular program includes only those nodes on which the program needs to be loaded. For each class route, a node is selected using a collective operation to be a load leader which accesses a file system to load the program associated with a class route and broadcasts the program via the class route to other nodes which require the program.

Abstract: Methods, apparatus, and computer program products are disclosed for debugging a high performance computing program by gathering lists of addresses of calling instructions for a plurality of threads of execution of the program, assigning the threads to groups in dependence upon the addresses, and displaying the groups to identify defective threads.

Abstract: Power throttling may be used to conserve power and reduce heat in a parallel computing environment. Compute nodes in the parallel computing environment may be organized into groups based on, for example, whether they execute tasks of the same job or receive power from the same converter. Once one of compute nodes in the group detects that a parameter (i.e., temperature, current, power consumption, etc.) has exceeded a first threshold, power throttling on all the nodes in the group may be activated. However, before deactivating power throttling, a plurality of parameters associated with the group of compute nodes may be monitored to ensure they are all below a second threshold. If so, the power throttling for all of the compute nodes is deactivated.

Abstract: Power throttling may be used to conserve power and reduce heat in a parallel computing environment. Compute nodes in the parallel computing environment may be organized into groups based on, for example, whether they execute tasks of the same job or receive power from the same converter. Once one of compute nodes in the group detects that a parameter (i.e., temperature, current, power consumption, etc.) has exceeded a first threshold, power throttling on all the nodes in the group may be activated. However, before deactivating power throttling, a plurality of parameters associated with the group of compute nodes may be monitored to ensure they are all below a second threshold. If so, the power throttling for all of the compute nodes is deactivated.

Abstract: Computer program product and system to limit core file generation in a massively parallel computing system comprising a plurality of compute nodes each executing at least one task, of a plurality of tasks, by: upon determining that a first task executing on a first compute node has failed, performing an atomic load and increment operation on a core file count; generating a first core file upon determining that the core file count is below a predefined threshold; and not generating the first core file upon determining that the core file count is not below the predefined threshold.

Abstract: Computer program product and system to limit core file generation in a massively parallel computing system comprising a plurality of compute nodes each executing at least one task, of a plurality of tasks, by: upon determining that a first task executing on a first compute node has failed, performing an atomic load and increment operation on a core file count; generating a first core file upon determining that the core file count is below a predefined threshold; and not generating the first core file upon determining that the core file count is not below the predefined threshold.

Abstract: A method and system for providing a memory access check on a processor including the steps of detecting accesses to a memory device including level-1 cache using a wakeup unit. The method includes invalidating level-1 cache ranges corresponding to a guard page, and configuring a plurality of wakeup address compare (WAC) registers to allow access to selected WAC registers. The method selects one of the plurality of WAC registers, and sets up a WAC register related to the guard page. The method configures the wakeup unit to interrupt on access of the selected WAC register. The method detects access of the memory device using the wakeup unit when a guard page is violated. The method generates an interrupt to the core using the wakeup unit, and determines the source of the interrupt. The method detects the activated WAC registers assigned to the violated guard page, and initiates a response.

Abstract: In an embodiment, asynchronous conflict events are received during a previous rollback period. Each of the asynchronous conflict events represent conflicts encountered by speculative execution of a first plurality of work units and may be received out-of-order. During a current rollback period, a first work unit is determined whose speculative execution raised one of the asynchronous conflict events, and the first work unit is older than all other of the first plurality of work units. A second plurality of work units are determined, whose ages are equal to or older than the first work unit, wherein each of the second plurality of work units are assigned to respective executing threads. Rollbacks of the second plurality of work units are performed. After the rollbacks of the second plurality of work units are performed, speculative executions of the second plurality of work units are initiated in age order, from oldest to youngest.

Abstract: A shared address space on a compute node stores data received from a network and data to transmit to the network. The shared address space includes an application buffer that can be directly operated upon by a plurality of processes, for instance, running on different cores on the compute node. A shared counter is used for one or more of signaling arrival of the data across the plurality of processes running on the compute node, signaling completion of an operation performed by one or more of the plurality of processes, obtaining reservation slots by one or more of the plurality of processes, or combinations thereof.

Abstract: Aggregating job exit statuses of a plurality of compute nodes executing a parallel application, including: identifying a subset of compute nodes in the parallel computer to execute the parallel application; selecting one compute node in the subset of compute nodes in the parallel computer as a job leader compute node; initiating execution of the parallel application on the subset of compute nodes; receiving an exit status from each compute node in the subset of compute nodes, where the exit status for each compute node includes information describing execution of some portion of the parallel application by the compute node; aggregating each exit status from each compute node in the subset of compute nodes; and sending an aggregated exit status for the subset of compute nodes in the parallel computer.

Abstract: Fixing a problem is usually greatly aided if the problem is reproducible. To ensure reproducibility of a multiprocessor system, the following aspects are proposed: a deterministic system start state, a single system clock, phase alignment of clocks in the system, system-wide synchronization events, reproducible execution of system components, deterministic chip interfaces, zero-impact communication with the system, precise stop of the system and a scan of the system state.

Abstract: Collectively loading an application in a parallel computer, the parallel computer comprising a plurality of compute nodes, including: identifying, by a parallel computer control system, a subset of compute nodes in the parallel computer to execute a job; selecting, by the parallel computer control system, one of the subset of compute nodes in the parallel computer as a job leader compute node; retrieving, by the job leader compute node from computer memory, an application for executing the job; and broadcasting, by the job leader to the subset of compute nodes in the parallel computer, the application for executing the job.

Abstract: Methods, apparatus, and computer program products are disclosed for debugging a high performance computing program by gathering lists of addresses of calling instructions for a plurality of threads of execution of the program, assigning the threads to groups in dependence upon the addresses, and displaying the groups to identify defective threads.