Emulation of abstracted DIMMS using abstracted DRAMS

• US 8,631,193 B2
• Filed: 05/17/2012
• Issued: 01/14/2014
• Est. Priority Date: 02/21/2008
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Smith, Michael John Sebastian, Rajan, Suresh Natarajan, Wang, David T
• Primary Examiner(s): Bansal, Gurtej
• Application Number:
  US13/473,827
• Publication Number:
  US 20120233395A1
• Time in Patent Office: 607 Days
• Field of Search: 711/5, 711/105, 711/167, 365/189.2
• US Class Current: 711/105
• CPC Class Codes: G06F 13/4239 with asynchronous protocol
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

One embodiment of the present invention sets forth an abstracted memory subsystem comprising abstracted memories, which each may be configured to present memory related characteristics onto a memory system interface. The characteristics can be presented on the memory system interface via logic signals or protocol exchanges, and the characteristics may include any one or more of, an address space, a protocol, a memory type, a power management rule, a number of pipeline stages, a number of banks, a mapping to physical banks, a number of ranks, a timing characteristic, an address decoding option, a bus turnaround time parameter, an additional signal assertion, a sub-rank, a number of planes, or other memory-related characteristics. Some embodiments include an intelligent register device and/or, an intelligent buffer device. One advantage of the disclosed subsystem is that memory performance may be optimized regardless of the specific protocols used by the underlying memory hardware devices.

Claims

1. A sub-system comprising:

a memory controller configured to be connected to both a first Dual In-line Memory Module (DIMM) and a second DIMM, wherein the memory controller is configured to present a first set of chip select signals to the first DIMM and a distinct second set of chip select signals to the second DIMM; and

a physical DIMM comprising an intelligent buffer and a collection of DRAM behind the intelligent buffer;

wherein the intelligent buffer is configured to

communicate with the memory controller,

operate a first subset of the collection of DRAM as a first abstracted DIMM (aDIMM) and a second subset of the collection of DRAM as a second aDIMM, and

present to the memory controller the first aDIMM as the first DIMM and the second aDIMM as the second DIMM;

wherein the physical DIMM and the intelligent buffer are configured to receive the first set of chip select signals and the second set of chip select signals from the memory controller; and

wherein the intelligent buffer is configured to provide the first set of chip select signals to the first subset of the collection of DRAM of the first aDIMM and to provide the second set of chip select signals to the second subset of the collection of DRAM of the second aDIMM.

2. The sub-system of claim 1, wherein the intelligent buffer is configured to present to the memory controller a first memory capacity for the first subset of the collection of DRAM of the first aDIMM, and a second memory capacity for the second subset of the collection of DRAM of the second aDIMM, and wherein a sum of the first and the second memory capacity is less than a total memory capacity of the collection of DRAM.

3. The sub-system in claim 1, wherein the intelligent buffer is configured to present to the memory controller a first set of characteristics associated with the first aDIMM and a distinct second set of characteristics associated with the second aDIMM.

4. The sub-system of claim 3, wherein the first and the second set of characteristics include sizes of memory address space, latency parameters, configuration characteristics, the power management modes, or the timing parameters.

5. The sub-system of claim 1, wherein the intelligent buffer is configured to emulate one or more of physical DRAM in the collection of DRAM as an abstracted DRAM (aDRAM).

6. The sub-system of claim 5, wherein the aDRAM uses a different protocol as compared with the memory controller, and wherein the intelligent buffer is configured to perform protocol translation between the aDRAM and the memory controller.

7. The sub-system of claim 5, wherein the intelligent buffer is configured to provide additional signals not presented by the memory controller to the aDRAM in order to control characteristics of the aDRAM.

8. The sub-system of claim 5, wherein the intelligent buffer is configured to provide the first and the second set of chip select signals as a highest bit in row address bits associated with the collection of DRAM.

9. The sub-system in claim 5, wherein the intelligent buffer is configured to present to the memory controller a DRAM type associated with the aDRAM, wherein the DRAM type is different from a DRAM type associated with the one or more physical DRAM.

10. The sub-system in claim 9, wherein the DRAM type associated with the aDRAM includes a DDR2 memory, a DDR3 memory, a GDDR5 memory, a LPDDR2 memory, a GDDR3 memory, a NOR flash memory, or a NAND flash memory.

11. The sub-system of claim 5, wherein the intelligent buffer is configured to provide a clock-enable (CKE) signal to the aDRAM in order to control timing parameters of the aDRAM.

12. The sub-system of claim 11, wherein the timing parameters include at least one of a tRP timing, a tRCD timing, a TWL timing, a tRFC timing, a tCKE timing, a tXP timing, a tXARD timing, a TXRDS timing, a tAL timing, a tFAW timing, a tRAS timing, a tRC timing, a tRRD timing, a tRTP timing, a tWR timing, or a tWTR timing.

13. The sub-system of claim 11, wherein the first subset of the collection of DRAM of the first aDIMM include the aDRAM, and wherein the intelligent buffer is configured to provide the CKE signal and at least one of the first set of chip select signals to the aDRAM in order to control power management modes of the aDRAM.

14. The sub-system of claim 13, wherein the intelligent buffer is configured to present to the memory controller a first set of characteristics associated with the aDRAM at an earlier segment of time, and to present to the memory controller a distinct second set of characteristics associated with the aDRAM at a later segment of time.

15. The sub-system of claim 14, wherein the first and the second set of characteristics include sizes of memory address space, latency parameters, configuration characteristics, the power management modes, or the timing parameters.

16. A memory module comprising:

a physical DIMM comprising an intelligent buffer and a collection of DRAM behind the intelligent buffer;

wherein the intelligent buffer is configured to

communicate with a memory controller,

operate a first subset of the collection of DRAM as a first abstracted DIMM (aDIMM) and a second subset of the collection of DRAM as a second aDIMM, and

present to the memory controller the first aDIMM as a first DIMM and the second aDIMM as a second DIMM;

wherein the physical DIMM and the intelligent buffer are configured to receive the first set of chip select signals and the second set of chip select signals from the memory controller; and

wherein the intelligent buffer is configured to provide the first set of chip select signals to the first subset of the collection of DRAM of the first aDIMM and to provide the second set of chip select signals to the second subset of the collection of DRAM of the second aDIMM.

17. The memory module of claim 16, wherein the intelligent buffer is configured to emulate one or more of physical DRAM in the collection of DRAM as an abstracted DRAM (aDRAM).

18. The memory module of claim 17, wherein the aDRAM uses a different protocol as compared with the memory controller, and wherein the intelligent buffer is configured to perform protocol translation between the aDRAM and the memory controller.

19. The memory module of claim 17, wherein the intelligent buffer is configured to provide a clock-enable (CKE) signal to the aDRAM in order to control timing parameters of the aDRAM, and wherein the timing parameters include at least one of a tRP timing, a tRCD timing, a TWL timing, a tRFC timing, a tCKE timing, a tXP timing, a tXARD timing, a TXRDS timing, a tAL timing, a tFAW timing, a tRAS timing, a tRC timing, a tRRD timing, a tRTP timing, a tWR timing, or a tWTR timing.

20. The memory module of claim 19, wherein the DRAM of the first aDIMM include the aDRAM, and wherein the intelligent buffer is configured to provide the CKE signal and at least one of the first set of chip select signals to the aDRAM in order to control power management modes of the aDRAM.