International Business Machines Corporation

Peichum Peter Liu

Takeshi Yamazaki

Charles Ray Johns

Michael Norman Day

Thuong Quang Truong

David Mui

Matthew Edward King

James Allan Kahle

Harm Peter Hofstee

An apparatus and a computer program product are provided for completing a plurality of (direct memory access) DMA commands in a computer system. It is determined whether the DMA commands are chained together as a list DMA command. Upon a determination that the DMA commands are chained together as a list DMA command, it is also determined whether a current list element of the list DMA command is fenced. Upon a determination that the current list element is not fenced, a next list element is fetched and processed before the current list element has been completed.

Apparatus, computer program product, and system for completing a plurality of chained list DMA commands that include a fenced list DMA command element

The present invention provides for atomic update primitives in an asymmetric single-chip heterogeneous multiprocessor computer system having a shared memory with DMA transfers. At least one lock line command is generated from a set comprising a get lock line command with reservation, a put lock line conditional command, and a put lock line unconditional command.

Method to provide atomic update primitives in an asymmetric heterogeneous multiprocessor environment

The present invention provides for a system comprising a DMA queue configured to receive a DMA command comprising a tag, wherein the tag belongs to one of a plurality of tag groups. A counter couples to the DMA queue and is configured to increment a tag group count of the tag group to which the tag belongs upon receipt of the DMA command by the DMA queue and to decrement the tag group count upon execution of the DMA command. A tag group count status register couples to the counter and is configured to store the tag group count for each of the plurality of tag groups. And the tag group count status register is further configured to receive a request for a tag group status and to respond to the request for the tag group status.

System for asynchronous DMA command completion notification wherein the DMA command comprising a tag belongs to a plurality of tag groups

A method, an apparatus, and a computer program product are provided for completing a plurality of (direct memory access) DMA commands in a computer system. It is determined whether the DMA commands are chained together as a list DMA command. Upon a determination that the DMA commands are chained together as a list DMA command, it is also determined whether a current list element of the list DMA command is fenced. Upon a determination that the current list element is not fenced, a next list element is fetched and processed before the current list element has been completed.

Method for completing a plurality of chained list DMA commands that include a fenced list DMA command element

A DMA controller (DMAC) for handling a list DMA command in a computer system is provided. The computer system has at least one processor and a system memory, the list DMA command relates to an effective address (EA) of the system memory, and the at least one processor has a local storage. The DMAC includes a DMA command queue (DMAQ) coupled to the local storage and configured to receive the list DMA command from the local storage and to enqueue the list DMA command. An issue logic is coupled to the DMAQ and configured to issue an issue request to the DMAQ. A request interface logic (RIL) is coupled to the DMAQ and configured to read the list DMA command based on the issue request. The RIL is further coupled to the local storage and configured to send a fetch request to the local storage to initiate a fetch of a list element of the list DMA command from the local storage to the DMAQ. Each list element comprises a stall bit indicating whether the list element is fenced and a DMA completion logic (DCL) is coupled to the at least one processor, the issue logic, and the RIL, and configured to indicate completion of all outstanding bus requests relating to the list element.

Non-fenced list DMA command mechanism

A method and an apparatus are provided for handling a list DMA command in a computer system. The list DMA command relates to an effective address (EA) of a system memory. At least one processor in the system has a local storage. The list DMA command is queued in a DMA queue (DMAQ). A list element is fetched from the local storage to the DMAQ. The list DMA command is read from the DMAQ. A bus request is issued for the list element. If the bus request is a last request, it is determined whether a current list element is a last list element. If the current list element is not the last list element, it is determined whether the current list element is fenced. If the current list element is not fenced, a next list element is fetched regardless of whether all outstanding requests are completed.

The present invention provides for asynchronous DMA command completion notification in a computer system. A command tag, associated with a plurality DMA command is generated. A DMA data movement command having the command tag is grouped with another DMA data movement command having the command tag. DMA commands belonging to the same tag group are monitored to see whether all DMA commands of the same tag group are completed.

System and method asynchronous DMA command completion notification by accessing register via attached processing unit to determine progress of DMA command

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Austin, TX, United States of America

Peichum Peter Liu