International Business Machines Corporation

Deryck X Hong

Hanhong Xue

Chulho Kim

Tsai-Yang Jea

Uman Chan

Hung Q Thai

Abhinav Vishnu

Zenon J Piatek

Peter H Hochschild

Rama Krishna Govindaraju

John Scott Houston

Piyush Chaudhary

Jang-Soo Lee

Leonard W Helmer, Jr

Steven J Martin

Richard J Coppinger

Jason E Goscinski

Yuqing Zhu

A message flow controller limits a process from passing a new message in a reliable message passing layer from a source node to at least one destination node while a total number of in-flight messages for the process meets a first level limit. The message flow controller limits the new message from passing from the source node to a particular destination node from among a plurality of destination nodes while a total number of in-flight messages to the particular destination node meets a second level limit. Responsive to the total number of in-flight messages to the particular destination node not meeting the second level limit, the message flow controller only sends a new packet from among at least one packet for the new message to the particular destination node while a total number of in-flight packets for the new message is less than a third level limit.

Flow control for reliable message passing

In a multinode data processing system in which the nodes communicate with one another via communication adapters over a network or switch, the adapters are provided with a dual register mechanism for tracking microcode task status. Upon the issuance of a disruptive command that requires attention from one of the nodes, the task status maintained in one register is copied to the snapshot register. As tasks within the adapter are completed, both registers are updated, thus providing a mechanism for the nodes to determine that all tasks active at the time of the disruptive command have completed. This means that the nodes now have a mechanism for determining, as soon as possible, that all tasks that are active when a disruptive command occurs have completed, thus allowing the data processing node to perform such operations as releasing system memory that is associated with the disruptive command, thus eliminating temporal overhead that can affect performance.

Snapshot interface operations

This present invention provides a portable user space application release/reacquire of adapter resources for a given job on a node using information in a network resource table. The information in the network resource table is obtained when a user space application is loaded by some resource manager. The present invention provides a portable solution that will work for any interconnect where adapter resources need to be freed and reacquired without having to write a specific function in the device driver. In the present invention, the preemption request is done on a job basis using a key or 'job key' that was previously loaded when the user space application or job originally requested the adapter resources. This is done for each OS instance where the job is run.

Managing preemption in a parallel computing system

A method, system, and computer program product are provided for managing a cache. A region to be stored within the cache is received. The cache includes multiple regions and each of the regions is defined by memory ranges having a starting index and an ending index. The region that has been received is stored in the cache in accordance with a cache invariant. The cache invariant guarantees that at any given point in time the regions in the cache are stored in a given order and none of the regions are completely contained within any other of the regions.

Managing a region cache

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Jackson Heights, NY, United States of America

Deryck X Hong