US 7,680,129 B2Granted

Preemptive retransmission of buffered data in a network

AssigneeInternational Business Machines Corporation

InventorsCarlos Francisco Fuente, William James Scales, William John Passingham, Robert Michael Jones

Life of this patent

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Abstract

An apparatus for data transmission over a network includes a buffer and a timer mechanism for timing an optimum interval (less than the round-trip error response delay) for retransmission of data. A first accessor accesses data in the buffer for transmission and starts a first timeout clock. Second or further accessors of the buffer are responsive to a timeout to access the data, start a timeout clock and attempt to transmit the data on a path avoiding path elements used by prior accessors. A counter increments and decrements a count of the references to the buffer by accessors and signals when the count reaches zero. A memory manager returns the buffer to a free buffer pool responsive to the reference counter signaling that the count has reached zero. An analysis mechanism can be used to determine the optimum interval and tune the timer mechanism.

Claims17

Dependent claims

An apparatus for data transmission comprising:

a buffer storing a data item to be transmitted to a receiver, wherein the buffer is configured to be pinned when in use by a hardware device and the buffer is configured to be pinned until a transmission from the hardware device is completed with one of a definite success and a definite failure, wherein when the buffer is pinned virtual memory used for the buffer is forced to remain real;
a plurality of hardware resources segregated into a plurality of independent transmission paths;
a timer mechanism for timing a predetermined optimum interval for a retransmission of the data item to the receiver, the predetermined optimum interval being less than a round-trip time required for receipt of an error condition from the network, the timer mechanism further signaling an end of the predetermined optimum interval;
a memory manager configured to maintain a reference count of concurrent accessors;
a first accessor of the buffer to access the data item for a first transmission and to start a first timeout clock set to the predetermined optimum interval;
a second accessor of the buffer responsive to the signaling of the end of the predetermined optimum interval by the timer mechanism to access the data item for the retransmission and to start a second timeout clock set to the predetermined optimum interval, the second accessor attempting to select a path for transmission of the data item avoiding use of path elements used by the first accessor, wherein the memory manager is further configured to lock the buffer during write activity, to permit read access to the buffer by the first accessor and the second accessor and to return the buffer to a free buffer pool when the reference count reaches zero;
a network monitoring data analyzer configured to analyze data for the apparatus;
and
an interval tuner configured to tune the predetermined optimum interval timed by the timer mechanism.

6 more elements

A computer program product comprising a computer readable medium being a non-transitory signal storing a computer program, where the computer program when executed on a computer causes the computer to:

store in a buffer a data item to be transmitted to a receiver, pin the buffer when in use by a hardware device until a transmission from the hardware device is completed with one of a definite success and a definite failure, and force virtual memory to remain real when the buffer is pinned;
configure a memory manager to maintain a reference count of concurrent accessors;
access the data item in the buffer with a first accessor for a first transmission of the data item to a receiver through a network;
start a first timeout clock set to time-out after an interval that is less than a round-trip time required for receipt of an error condition from the network;
responsive to a signal indicating that the first timeout clock has timed-out, access the data item in the buffer with a second accessor for a second transmission of the data item to the receiver through the network, where the second accessor selects a path for the second transmission from among a plurality of transmission paths that avoids use of at least one network path element used by the first accessor during the first transmission;
start a second timeout clock set to time-out after the interval;
and
control the memory manager to lock the buffer during write activity, to permit read access to the buffer by the first accessor and the second accessor and to return the buffer to a free buffer pool when the reference count reaches zero.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/191,432Filed 27 Jul 2005 · continuation
Priority: GB 0302117.730 Jan 2003
Published: US 2005/0265370 A11 Dec 2005
Granted: 16 Mar 2010
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H04L 45/28
Routing or path finding of packets in data switching networks: using route fault recovery
H04L 45/247
Multipath: using M:N active or standby paths
H04L 47/283
In relation to timing considerations: in response to processing delays, e.g. caused by jitter or round trip time [RTT]
H04L 69/16
Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass:…