Method and system for dynamic buffering of disk I/O command chains

• US 8,595,394 B1
• Filed: 12/01/2003
• Issued: 11/26/2013
• Est. Priority Date: 06/26/2003
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Danilak, Radoslav, Rao, Krishnaraj S.
• Primary Examiner(s): LEE, CHUN KUAN
• Application Number:
  US10/726,151
• Time in Patent Office: 3,648 Days
• Field of Search: 710/5, 710/29, 710 52- 53, 710/57, 710/26, 711/100, 711/154, 3 5/7
• US Class Current: 710/57
• CPC Class Codes: G06F 13/385 for adaptation of a particular data processing system to different peripheral devices
• CPC Class Codes: G06F 3/061 Improving I/O performance
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0676 Magnetic disk device

Abstract

A method for dynamic buffering of disk I/O command chains for a computer system. The method includes receiving a plurality of disk I/O command chains from at least one thread executing on a processor of the computer system. A respective plurality of pointers for the disk I/O command chains are stored in a buffer of a disk controller. The disk I/O command chains are accessed for execution by the disk controller by serially accessing the pointers in the buffer.

Claims

1. A method comprising:

receiving a plurality of disk I/O command chains and respective start address pointers contemporaneously by re-entrant code from a plurality of threads executing on a processor of a computing system;

storing the plurality of disk I/O command chains, wherein each disk I/O command chain is stored separately from each other without implementing an appending operation;

storing the plurality of respective start address pointers for the plurality of stored disk I/O command chains on a first-in-first-out basis in a buffer of a disk controller for a disk drive using a hardware implemented lock function of the processor and not an operating system lock function to check a fullness of the buffer prior to adding new start address pointers, and using the operating system lock function to handle the buffer after a buffer full condition occurs; and

dynamically accessing and executing the plurality of stored disk I/O command chains by the disk controller by serially accessing on the first-in-first-out basis of the plurality of respective start address pointers in the buffer, wherein the plurality of disk I/O command chains are accessed and executed asynchronously with respect to storing the plurality of disk I/O command chains.

2. The method of claim 1, further comprising:

storing, concurrently with storing the plurality of independent disk I/O command chains, in the buffer, the plurality of respective start address pointers for the independent disk I/O command chains stored in the system memory when the buffer is not full; and

storing, concurrently with storing the plurality of independent disk I/O command chains, in the system memory, the plurality of respective start address pointers for the independent disk I/O command chains stored in the system memory when the buffer is full.

3. A non-transitory computer readable media having computer readable code which when executed by a processor of a computer system cause the computer system to implement a method for dynamic buffering of disk I/O command chains for the computer system, comprising:

receiving the plurality of disk I/O command chains and respective start address pointers contemporaneously by re-entrant code from a plurality of threads executing on the processor of the computing system;

storing the plurality of disk I/O command chains, wherein each disk I/O command chain is stored separately from each other without implementing an appending operation;

storing the plurality of respective start address pointers for the plurality of stored disk I/O command chains on a first-in-first-out basis in a buffer of a disk controller for a disk drive using a hardware implemented lock function of the processor and not an operating system lock function to check a fullness of the buffer prior to adding new start address pointers, and using the operating system lock function to handle the buffer after a buffer full condition occurs; and

dynamically accessing and executing the plurality of stored disk I/O command chains by the disk controller by serially accessing on the first-in-first-out basis of the plurality of respective start address pointers in the buffer, wherein the plurality of disk I/O command chains are accessed and executed asynchronously with respect to storing the plurality of disk I/O command chains.

4. The non-transitory computer readable media of claim 3, wherein, the disk controller accesses the independent disk command chains for execution in accordance with an order of the start address pointers in the buffer.

5. A computer system for dynamic buffering of CPB (command parameter block) chains, comprising:

a processor;

a system memory coupled to the processor;

a bridge component coupled to the processor; and

a disk controller for a disk drive coupled to the bridge component, wherein the processor execute software code stored in the system memory, the software code causing the computer system to implement a method comprising;

receiving a plurality of CPB chains and respective start address pointers contemporaneously by re-entrant code from a plurality of threads executing on the processor of the computing system;

storing the plurality of CPB chains, wherein each CPB chain is stored separately from each other without implementing an appending operation;

storing the plurality of respective start address pointers for the plurality of stored CPB chains on a first-in-first-out basis in a buffer of the disk controller for the disk drive using a hardware implemented lock function of the processor and not an operating system lock function to check a fullness of the buffer prior to adding new start address pointers, and using the operating system lock function to handle the buffer after a buffer full condition occurs; and

dynamically accessing and executing the plurality of stored CPB chains by the disk controller by serially accessing on the first-in-first-out basis of the plurality of respective start address pointers in the buffer, wherein the plurality of CPB chains are accessed and executed asynchronously with respect to storing the plurality of CPB chains.

6. The system of claim 5, wherein corresponding CPBs in each chain of CPBs are linked using next CPB pointers.

7. The system of claim 5, wherein the respective start address pointers for the independent CPB chains comprise pointers to first CPBs of the CPB chains.

8. The system of claim 5, wherein the storing of the respective start address pointers for the independent CPB chains in the pointer buffer of the disk controller comprises

storing the respective start address pointers for the independent CPB chains in the system memory if the pointer buffer is full;

and

incrementally adding the respective start address pointers for the independent CPB chains to the pointer buffer when a portion of the pointer buffer frees up.