Method and apparatus for determining priorities in direct memory access device having multiple direct memory access request blocks

• US 20080183913A1
• Filed: 08/31/2007
• Published: 07/31/2008
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ryu, Eun-jin, Lim, Jae-young, Kang, Dong-soo
• Granted Patent: US 8,065,447 B2
• Time in Patent Office: Days
• US Class Current: 710/25
• CPC Class Codes: G06F 13/28 using burst mode transfer, e.g. direct memory access DMA, cycle steal G06F13/32 takes precedence

Abstract

A priority determining method and apparatus can reduce a total waiting time of DMA request blocks by granting priority to each of Direct Memory Access (DMA) request blocks transmitting a DMA request signal, based on Data Transfer Amounts (DTAs) of the DMA request blocks and Arrival Times (ATs) of the DMA request signals, counting the number of priority changes of each of DMA request blocks whose priority is changed in the priority granting process, and if a DMA request signal is received from a new DMA request block, determining priorities of the DMA request blocks based on the counted the number of priority changes.

Claims

1. A priority determining method, comprising:

granting priority to each of Direct Memory Access (DMA) request blocks transmitting a DMA request signal, based on Data Transfer Amounts (DTAs) of the DMA request blocks and Arrival Times (ATs) of the DMA request signals;

counting the number of priority changes of each of DMA request blocks whose priority is changed in (a); and

if a DMA request signal is received from a new DMA request block, determining priorities of the DMA request blocks based on the counted numbers of priority changes.

2. The priority determining method of claim 1, wherein the determining priorities of the DMA request blocks comprises:

comparing the counted number and a predetermined threshold with respect to each DMA request block whose priority is changed; and

determining priorities of the DMA request blocks and the new DMA request block based on ATs of the DMA request signals according to a result of the comparison.

3. The priority determining method of claim 2, wherein if the number of priority changes of one of the DMA request blocks whose priority is changed is equal to or greater than the predetermined threshold in the determining priorities, the priorities of the DMA request blocks are maintained as the priorities, and priority of the new DMA request block is determined based on an AT of its DMA request signal.

4. The priority determining method of claim 1, wherein the determining priorities of the DMA request blocks comprises:

comparing the counted number and the predetermined threshold with respect to each DMA request block whose priority is changed; and

determining priorities of the DMA request blocks and the new DMA request block based on DTAs according to a result of the comparison.

5. The priority determining method of claim 4, wherein if the number of priority changes of one of the DMA request blocks whose priority is changed is equal to or greater than the predetermined threshold in the determining priorities, the priority of the DMA request block whose number of priority changes is equal to or greater than the predetermined threshold among the DMA request blocks is maintained as it is and priorities of the new DMA request block and the other DMA request blocks remaining by excluding the DMA request block maintaining its existing priority are determined based on DTAs.

6. The priority determining method of claim 1, wherein the granting priority comprises granting higher priority to a DMA request block having a smaller DTA.

7. The priority determining method of claim 1, wherein the new DMA request block and the DMA request blocks are processors which can perform data computation.

8. The priority determining method of claim 1, wherein the predetermined threshold can be changed.

9. A computer readable recording medium storing a computer readable program for executing the priority determining method of claim 1.

10. A priority determining apparatus, comprising:

a priority pre-processing unit to grant priority to each of Direct Memory Access (DMA) request blocks transmitting a DMA request signal, based on Data Transfer Amounts (DTAs) of the DMA request blocks and Arrival Times (ATs) of the DMA request signals;

a counter to count the number of priority changes of each of DMA request blocks whose priority is changed in the priority granting process; and

a priority determining module to determine priorities of the DMA request blocks based on the counted numbers when a DMA request signal is received from a new DMA request block.

11. The priority determining apparatus of claim 10, wherein the priority determining module comprises:

a comparator to compare the counted number and a predetermined threshold with respect to each DMA request block whose priority is changed; and

a priority determiner to determine priorities of the DMA request blocks and the new DMA request block based on ATs of the DMA request signals according to a result of the comparison.

12. The priority determining apparatus of claim 11, wherein if the number of priority changes of one of the DMA request blocks whose priority is changed is equal to or greater than the predetermined threshold, the priority determiner maintains the priorities of the DMA request blocks as the priorities and determines priority of the new DMA request block based on an AT of its DMA request signal.

13. The priority determining apparatus of claim 10, wherein the priority determining module comprises:

a comparator to compare the counted number and the predetermined threshold with respect to each DMA request block whose priority is changed; and

a priority determiner to determine priorities of the DMA request blocks and the new DMA request block based on DTAs according to a result of the comparison.

14. The priority determining apparatus of claim 13, wherein if the number of priority changes of one of the DMA request blocks whose priority is changed is equal to or greater than the predetermined threshold, the priority determiner maintains the priority of the DMA request block whose number of priority changes is equal to or greater than the predetermined threshold among the DMA request blocks as it is and determines priorities of the new DMA request block and the other DMA request blocks remaining by excluding the DMA request block maintaining its existing priority based on DTAs.

15. The priority determining apparatus of claim 10, wherein the priority pre-processing unit grants higher priority to a DMA request block having a smaller DTA.

16. The priority determining apparatus of claim 10, wherein the new DMA request block and the DMA request blocks are processors which can perform data computation.

17. The priority determining apparatus of claim 10, wherein the predetermined threshold can be changed.

18. A priority determining method, comprising:

granting priority to each of Direct Memory Access (DMA) request blocks; and

transmitting a DMA request signal, based on Data Transfer Amounts (DTAs) of the DMA request blocks, Arrival Times (ATs), and a number of priority changes of each of the DMA request blocks.