International Business Machines Corporation

Google Inc.

Rajeev Sivaram

Chulho Kim

Hanhong Xue

Robert Sidney Blackmore

Rama Krishna Govindaraju

Myung Mun Bae

Paul D DiNicola

Scott D Epter

Peter H Hochschild

Jay Robert Herring

Piyush Chaudhary

Richard R Treumann

Xin Chen

Amy Xin Chen

Craig Brian Stunkel

Sridhar Raman

Systems and methods are provided for managing congestion at a destination host in a network. A transport layer system manages receive buffer for application processes running on the destination host. Upon receiving the first packet of a new message from a source host, the system determines if there is enough free space in the receive buffer at the destination host to be reserved for the entire message. The system allocates receive buffer for the entire message if there is enough free receive buffer space. If there is not enough free buffer space, the system drops the message and sends a negative acknowledgment to the source host. The source host pauses transmission to the destination host upon receiving the negative acknowledgment. The system sends a resume message to the source host when there is enough free buffer. The source host retransmits the dropped message upon receiving the resume message.

System and method for handling of destination host side congestion

Epoch numbers are maintained in a pair wise fashion at a plurality of communication endpoints to provide communication consistency and recovery from a range of failure conditions including total or partial node failure and subsequent recovery. Once an epoch state inconsistency is recognized, negotiation procedures provide an effective mechanism to reestablish valid communication links without the need to employ global variables which inherently possess greater transmission and overhead requirements needed to maintain communications. Renegotiation of recognizably valid epoch numbers occurs on a pair wise basis.

System and program product to recover from node failure/recovery incidents in distributed systems in which notification does not occur

Globally consistent information is locally provided to communications layers. Globally consistent information is stored in a Network Availability Matrix, which is locally accessible by a communications layer. If an event is detected, the communications layer is automatically notified by the Network Availability Matrix, and is able to use the information in the Network Availability Matrix to quickly take action.

Locally providing globally consistent information to communications layers

A barrier synchronization register, accessible to the nodes in a distributed data processing system, has portions thereof allotted to threads which are present in multiple groups. The barrier synchronization register portion allotted to a given thread has stored therein, over time, group identifier numbers. In this way the state space of a barrier synchronization register is shared over more than one group of process threads.

Effective use of a hardware barrier synchronization register for protocol synchronization

A method, an apparatus and a recording medium are provided for communicating message payload data, especially noncontiguous message data, from a first node of a network to a second node of the network in response to a request to transmit a message. Such method includes dividing the length of a data payload to be transmitted into a plurality of submessage payload lengths, i.e., into at least a first submessage payload length and a second submessage payload length. Then, a first ordered submessage is transmitted from the first node for delivery to the second node, the first ordered submessage having the first submessage payload length. A first state of an environment is then determined in the first node as if the step of transmitting the first ordered submessage were already completed. Without having to complete the step of transmitting the first ordered submessage, a second ordered submessage is then transmitted from the first node for delivery to the second node, the second submessage having the second submessage payload length, the second submessage being transmitted in a way that takes into account the first state of the environment in the first node.

Method and apparatus for striping message payload data over a network

A system and method to provide injection of important data directly into a processor's cache location when that processor has previously indicated interest in the data. The memory subsystem at a target processor will determine if the memory address of data to be written to a memory location associated with the target processor is found in a processor cache of the target processor. If it is determined that the memory address is found in a target processor's cache, the data will be directly written to that cache at the same time that the data is being provided to a location in main memory.

System and method for intelligent software-controlled cache injection

A protocol interface is provided for an active message protocol of a computing environment and a client process employing the active message protocol. The protocol interface includes an interface to a header handler function associated with the client process. The interface to the header handler function has parameters to be passed by and a parameter to be returned to the active message protocol when processing a message received through the active message protocol. The parameters to be passed include current message state information and current message type information for the received message. These parameters facilitate message-specific decisions by the header handler function about processing data of the message by the active message protocol. The parameter to be returned to the active message protocol instructs the active message protocol how to process the received message other than just where to store the message.

Interface method, system, and program product for facilitating layering of a data communications protocol over an active message layer protocol

A method and system for transferring noncontiguous messages group including assembling a set of data into a series of transmission packets, packaging a description of the layout of the transmission packets into description packets and then places each description packet into a local buffer while maintaining a count of the number of description packets, transfers each description packet into a transmit buffer for transmission to at least one receiving node, identifies the data packets, and forwards each data packet to the transmit buffer for transmission to the at least one receiving node. The receiving node receives the transmission packets, identifies each packet as a description packet or data packet, places the description packets in a local buffer for storage until the description is complete, places each description packet into a user data buffer, stores data packets in a local queue until the description is complete, then transfers the data packets to the user buffer.

Method and system for efficiently transferring a self-defined non-contiguous message in a one-sided communication model

Method to recover from node failure/recovery incidents in distributed systems in which notification does not occur

Lock-free queues of a shared memory environment are used to facilitate communication within that environment. The lock-free queues can be used for interprocess communication, as well as intraprocess communication. The lock-free queues are structured to minimize the use of atomic operations when performing operations on the queues, and to minimize the number of enqueue/dequeue operations to be performed on the queues.

Facilitating communication within shared memory environments using lock-free queues

The invention is a replication method that requires only one copy of a packet entering a multiport switch to be transmitted from the input port, the method acquiring the deadlock avoidance advantages of virtual cut-through operation. The goal is achieved via a central buffer, with replication occurring during the read of the chunk out of the central buffer by the output ports.

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West Orange, NJ, United States of America

Rajeev Sivaram