Hewlett-packard Development Company, L.P.

3par Inc.

Greg L Dykema

Christopher T Cheng

Michel P Cekleov

David Chu

David H Bassett

Joel Leon Lach

A first node includes a DMA engine for transferring data specified by a sequence of control blocks to a second node. When a control block does not require synchronization between memories, the DMA engine sends an end of transfer (EOT) message after the last datum, increments an EOT counter, and processes the next control block. When a control block requires synchronization and the EOT counter is at zero, the DMA engine sends an EOT with a flag after the last datum, increments the EOT counter, and waits for the EOT counter to return to zero before processing the next control block. A memory controller at the second node detects the EOT with or without a flag and generates an EOT acknowledgement with or without a flag. When a link interface at the second node detects the EOT acknowledgement with a flag, it sends an interrupt to a local processor complex.

Mechanisms for synchronizing data transfers between non-uniform memory architecture computers

A method is provided to align clock and data signals over a source-synchronous link. The method includes sending header data and a default clock signal over the link. The header indicates a start of a training packet and the default clock signal ensures that the header is received without error. The method further includes providing a long clock pulse, phase shifting the clock signal during the long clock pulse, and thereafter sending training data and the clock signal over the link. The above steps are repeated until the training data are received with error. At that point, the phase shift of the clock signal is saved as a boundary of an optimal alignment. The above steps are then repeated with the clock signal shifted in a different direction. Once another boundary is located, the boundary midpoint is saved as the phase shift that provides the optimal alignment.

Trainable link

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Redwood City, CA, United States of America

Greg L Dykema