US6324597B2
Expired / Lapsed
US
⏱️ 0.0 years remaining
Host controller interface descriptor fetching unit
Assignee: Sun Microsystems Inc
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Filing: 2001-01-11
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Granted: 2001-11-27
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Expires: 2021-01-11
Abstract
Abstract The present invention relates to a method and circuit for prefetching direct memory access descriptors from memory of a computer system, and storing the prefetched direct memory access descriptors within a unified descriptor memory for subsequent access by direct memory access controllers. The descriptors are generated by a central processing unit of the computer system while executing software applications. The descriptors define data transfer operations between memory of the computer system and input/output devices via direct memory access controllers. The direct memory access controllers generate requests for descriptors. Upon generation of a request, the unified descriptor memory is checked to determine whether the requested descriptor is contained therein. If the requested descriptor is contained within the unified descriptor memory, the request descriptor is provided to the requesting direct memory access controller. If, however, the requested descriptor is not stored within the unified descriptor memory, the system memory is accessed for the requested descriptor, and the requested descriptor is transferred from system memory to the unified descriptor memory in a block of descriptors each relating to the same context. After the requested descriptor is stored within the unified descriptor memory, the requested descriptor is provided to the requesting direct memory access controller.
Inventors
- 👤 Josh David Collier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:24
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/40052; H04L12/40058; G; G06; G06F; G06F13/00; G06F13/14; G06F13/20; G06F13/28; H04L12/40123
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
164 words
A computer system comprising: a central processing unit (CPU); a main memory coupled to the CPU; an I/O bus; a host controller interface coupled between the I/O bus and the main memory; wherein data is transferred between one or more I/O devices coupled to the I/O bus and the main memory using descriptors generated by the CPU and stored in the main memory; wherein the host controller interface comprises: a descriptor memory for storing descriptors, wherein the descriptor memory is configured to provide a requested descriptor when the requested descriptor is stored therein; and fetching circuitry coupled to the descriptor memory and operably coupled to the main memory, wherein when the requested descriptor is not stored in the descriptor memory, the fetching circuitry is configured to: (i) fetch a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor, and (ii) store the fetched plurality of descriptors within the descriptor memory.
Claim 2
Dependent Claim
164 words
A computer system comprising: a central processing unit (CPU); a main memory coupled to the CPU; an I/O bus; a host controller interface coupled between the I/O bus and the main memory; wherein data is transferred between one or more I/O devices coupled to the I/O bus and the main memory using descriptors generated by the CPU and stored in the main memory; wherein the host controller interface comprises: a descriptor memory for storing descriptors, wherein the descriptor memory is configured to provide a requested descriptor when the requested descriptor is stored therein; and fetching circuitry coupled to the descriptor memory and operably coupled to the main memory, wherein when the requested descriptor is not stored in the descriptor memory, the fetching circuitry is configured to: (i) fetch a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor, and (ii) store the fetched plurality of descriptors within the descriptor memory.
Claim 3
Dependent Claim
31 words
The computer system as recited in claim 1 , wherein the descriptors are direct memory access (DMA) descriptors each specifying a corresponding main memory location where data is to be accessed.
Claim 4
Independent Claim
101 words
A method for fetching descriptors from a main memory, comprising: receiving a request for a requested descriptor; searching a descriptor memory for the requested descriptor; providing the requested descriptor from the descriptor memory if the requested descriptor is found in the descriptor memory; performing the following if the requested descriptor is not found in the descriptor memory: fetching a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor; storing the fetched plurality of descriptors in the descriptor memory; and providing the requested descriptor from the descriptor memory.
Claim 5
Independent Claim
101 words
A method for fetching descriptors from a main memory, comprising: receiving a request for a requested descriptor; searching a descriptor memory for the requested descriptor; providing the requested descriptor from the descriptor memory if the requested descriptor is found in the descriptor memory; performing the following if the requested descriptor is not found in the descriptor memory: fetching a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor; storing the fetched plurality of descriptors in the descriptor memory; and providing the requested descriptor from the descriptor memory.
Claim 6
Dependent Claim
30 words
The method as recited in claim 3 , wherein the descriptors are direct memory access (DMA) descriptors each specifying a corresponding main memory location where data is to be accessed.
Claim 7
Dependent Claim
24 words
The method as recited in claim 4 , wherein the request for the requested descriptor is generated by a direct memory access (DMA) device.
Claim 8
Dependent Claim
29 words
The method as recited in claim 3 , further comprising flushing the requested descriptor from the descriptor memory following the providing of the requested descriptor from the descriptor memory.
Claim 9
Independent Claim
185 words
A method for fetching descriptors from a main memory, comprising: receiving a plurality of descriptor requests each identifying a requested descriptor, wherein the descriptor requests are active simultaneously; repeating the following such that the descriptor requests are satisfied sequentially: selecting a selected one of the descriptor requests; searching a descriptor memory for the requested descriptor identified by the selected one of the descriptor requests; providing the requested descriptor identified by the selected one of the descriptor requests from the descriptor memory if the requested descriptor identified by the selected one of the descriptor requests is found in the descriptor memory; performing the following if the requested descriptor identified by the selected one of the descriptor requests is not found in the descriptor memory: fetching a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor identified by the selected one of the descriptor requests; storing the fetched plurality of descriptors in the descriptor memory; and providing the requested descriptor identified by the selected one of the descriptor requests from the descriptor memory.
Claim 10
Independent Claim
185 words
A method for fetching descriptors from a main memory, comprising: receiving a plurality of descriptor requests each identifying a requested descriptor, wherein the descriptor requests are active simultaneously; repeating the following such that the descriptor requests are satisfied sequentially: selecting a selected one of the descriptor requests; searching a descriptor memory for the requested descriptor identified by the selected one of the descriptor requests; providing the requested descriptor identified by the selected one of the descriptor requests from the descriptor memory if the requested descriptor identified by the selected one of the descriptor requests is found in the descriptor memory; performing the following if the requested descriptor identified by the selected one of the descriptor requests is not found in the descriptor memory: fetching a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor identified by the selected one of the descriptor requests; storing the fetched plurality of descriptors in the descriptor memory; and providing the requested descriptor identified by the selected one of the descriptor requests from the descriptor memory.
Claim 11
Independent Claim
105 words
An apparatus for fetching descriptors from a main memory, comprising: a descriptor memory for storing descriptors, wherein the descriptor memory is configured to provide a requested descriptor when the requested descriptor is stored therein; and fetching circuitry coupled to the descriptor memory and operably coupled to the main memory, wherein when the requested descriptor is not stored in the descriptor memory, the fetching circuitry is configured to: (i) fetch a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor, and (ii) store the fetched plurality of descriptors within the descriptor memory.
Claim 12
Independent Claim
105 words
An apparatus for fetching descriptors from a main memory, comprising: a descriptor memory for storing descriptors, wherein the descriptor memory is configured to provide a requested descriptor when the requested descriptor is stored therein; and fetching circuitry coupled to the descriptor memory and operably coupled to the main memory, wherein when the requested descriptor is not stored in the descriptor memory, the fetching circuitry is configured to: (i) fetch a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor, and (ii) store the fetched plurality of descriptors within the descriptor memory.
Claim 13
Dependent Claim
30 words
The apparatus as recited in claim 8 , wherein the descriptors are direct memory access (DMA) descriptors each specifying a corresponding main memory location where data is to be accessed.
Claim 14
Dependent Claim
33 words
The apparatus as recited in claim 8 , wherein the descriptor memory is configured to respond to a request for the requested descriptor by searching for the requested descriptor within the descriptor memory.
Claim 15
Dependent Claim
29 words
The apparatus as recited in claim 10 , wherein if the requested descriptor is found in the descriptor memory, the descriptor memory is configured to provide the requested descriptor.
Claim 16
Dependent Claim
37 words
The apparatus as recited in claim 8 , wherein during the single data transfer operation the fetch circuitry provides an address to the main memory, and in response the main memory provides the fetched plurality of descriptors.
Claim 17
Dependent Claim
174 words
A descriptor fetch unit, comprising: a descriptor request arbiter coupled to receive one or more descriptor requests each identifying a requested descriptor, wherein the descriptor request arbiter is configured to provide a selected one of the descriptor requests; a descriptor memory for storing descriptors, wherein the descriptor memory is coupled to receive the selected one of the descriptor requests and configured to provide the requested descriptor identified by the selected one of the descriptor requests when the requested descriptor is stored therein; and a descriptor fetch controller coupled to the descriptor memory and operably coupled to a main memory, wherein if the requested descriptor identified by the selected one of the descriptor requests is not present within the descriptor memory the descriptor fetch controller is configured to: (i) fetch a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor identified by the selected one of the descriptor requests, and (ii) store the fetched plurality of descriptors within the descriptor memory.
Claim 18
Dependent Claim
174 words
A descriptor fetch unit, comprising: a descriptor request arbiter coupled to receive one or more descriptor requests each identifying a requested descriptor, wherein the descriptor request arbiter is configured to provide a selected one of the descriptor requests; a descriptor memory for storing descriptors, wherein the descriptor memory is coupled to receive the selected one of the descriptor requests and configured to provide the requested descriptor identified by the selected one of the descriptor requests when the requested descriptor is stored therein; and a descriptor fetch controller coupled to the descriptor memory and operably coupled to a main memory, wherein if the requested descriptor identified by the selected one of the descriptor requests is not present within the descriptor memory the descriptor fetch controller is configured to: (i) fetch a plurality of descriptors from the main memory during a single data transfer operation, wherein the fetched plurality of descriptors includes the requested descriptor identified by the selected one of the descriptor requests, and (ii) store the fetched plurality of descriptors within the descriptor memory.
Claim 19
Dependent Claim
32 words
The descriptor fetch unit as recited in claim 13 , wherein the descriptors are direct memory access (DMA) descriptors each specifying a corresponding main memory location where data is to be accessed.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-11-26 | 2005-05-28 | 2005-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-11-26 | 2009-05-28 | 2009-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-11-26 | 2013-05-28 | 2013-11-27 | $7700.00 | Window Closed / Lapsed |