Fetch operations in a disk drive control system
View Patent ↗A method and system for improving fetch operations between a micro-controller and a remote memory via a buffer manager in a disk drive control system comprising a micro-controller, a micro-controller cache system having a cache memory and a cache-control subsystem, and a buffer manager communicating with micro-controller cache system and remote memory. The invention includes receiving a data-request from micro-controller in cache control subsystem wherein the data-request comprises a request for at least one of instruction code and non-instruction data. The invention further includes providing the requested data to micro-controller if the requested data reside in cache memory, determining if the received data-request is for non-instruction data if requested data does not reside in cache memory, fetching the non-instruction data from remote memory by micro-controller cache system via buffer manager, and bypassing cache memory to preserve the contents of cache memory and provide the fetched non-instruction data to micro-controller.
1. In a disk drive comprising a micro-controller, a micro-controller cache system in communication with the micro-controller and having a cache memory, a remote memory, and a buffer manager in communication with the micro-controller cache system and the remote memory, a method of providing data requested by the micro-controller comprising:
sending a request for data from the micro-controller to the micro-controller cache system;
determining whether the data request corresponds to data cached in the cache memory;
determining whether the data request corresponds to an instruction code or non-instruction data; and
if the data request corresponds to an instruction code that is not cached in the cache memory:
fetching the instruction code from the remote memory via the buffer manager,
filling the cache memory with the instruction code, and
providing the cached instruction code to the micro-controller; and
if the data request corresponds to non-instruction data that is not cached in the cache memory:
fetching the non-instruction data from the remote memory via the buffer manager, and
sending the non-instruction data uncached from the buffer manager to the micro-controller via the micro-controller cache system.
2. The method of claim 1 , wherein determining whether the data request corresponds to an instruction code or non-instruction data is based on a signal received from the micro-controller.
3. The method of claim 1 , wherein fetching further comprises:
sending a micro-controller cache system request from the micro-controller cache system to the buffer manager;
accessing the remote memory from the buffer manager; and
retrieving data corresponding to the micro-controller cache system request from the remote memory.
4. The method of claim 1 , wherein the buffer manager is further in communication with a plurality of control system clients and provides client-requested data to the clients from the remote memory.
5. The method of claim 4 , wherein the plurality of control system clients comprises at least one of a disk subsystem, an error correction code subsystem, and a host interface subsystem.
6. The method of claim 1 , wherein the remote memory comprises a dynamic random access memory (DRAM).
7. The method of claim 1 , wherein filling the cache memory comprises burst filling the cache memory.
8. A disk drive control system comprising:
a micro-controller;
a remote memory;
a buffer manager in communication with the remote memory; and
a micro-controller cache system in communication with the micro-controller and the buffer manager and having a cache memory, the micro-controller cache system adapted to:
receive a request for data from the micro-controller;
determine whether the data request corresponds to data cached in the cache memory;
determine whether the data request corresponds to an instruction code or non-instruction data; and
if the data request corresponds to an instruction code that is not cached in the cache memory:
fetch the instruction code from the remote memory via the buffer manager,
fill the cache memory with the instruction code, and
provide the cached instruction code to the micro-controller; and
if the data request corresponds to non-instruction data that is not cached in the cache memory:
fetch the non-instruction data from the remote memory via the buffer manager, and
send the non-instruction data uncached from the buffer manager to the micro-controller via the micro-controller cache system.
9. The disk drive control system of claim 8 , wherein the micro-controller cache system is adapted to determine whether the data request corresponds to an instruction code or non-instruction data based on a signal received from the micro-controller.
10. The disk drive control system of claim 8 , wherein the micro-controller cache system is adapted to fetch data from the remote memory by:
sending a micro-controller cache system request to the buffer manager; and
receiving data corresponding to the micro-controller cache system request from the buffer manager.
11. The disk drive control system of claim 8 , wherein the buffer manager is further in communication with a plurality of control system clients and provides client-requested data to the clients from the remote memory.
12. The disk drive control system of claim 11 , wherein the plurality of control system clients comprises at least one of a disk subsystem, an error correction code subsystem, and a host interface subsystem.
13. The disk drive control system of claim 8 , wherein the remote memory comprises a dynamic random access memory (DRAM).
14. The disk drive control system of claim 8 , wherein the cache memory is filled with a burst fill.