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

• US 7,546,393 B2
• Filed: 04/02/2007
• Issued: 06/09/2009
• Est. Priority Date: 05/29/2003
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Johns, Charles Ray, Hofstee, Harm Peter, Liu, Peichum Peter, Truong, Thuong Quang, Yamazaki, Takeshi, Day, Michael Norman
• Primary Examiner(s): PEYTON, TAMMARA R
• Application Number:
  US11/695,436
• Publication Number:
  US 20070174509A1
• Time in Patent Office: 799 Days
• Field of Search: 710/5, 710/20, 710/22, 710/24, 710/62, 710/312
• US Class Current: 710/22
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence

Abstract

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.

Claims

1. 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 coupled to the DMA queue and 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 coupled to the counter and configured to store the tag group count for each of the plurality of tag groups;

and wherein 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.

2. The system of claim 1, further comprising an attached processing unit (APU) coupled to the DMA queue and configured:

to group DMA commands into tag groups;

to generate tags associated with the DMA commands;

to transmit the DMA command and associated tag to the DMA queue; and

to generate and transmit to the tag group count status register a request for tag group status.

3. The system of claim 1, further comprising a mask coupled to the tag group count register.

4. The system of claim 1, wherein the tag group count status register further comprises a tag status register configured to respond to the request for the tag group status.

5. The system of claim 1, further comprising a tag status register coupled to the mask and configured to respond to the request for the tag group status.

6. The system of claim 1, wherein the response indicates whether the tag group count is non-zero.

7. The system of claim 2, wherein the response indicates whether there are any DMA commands with tags belonging to the identified tag group that have not executed.