Buffering of Data Transfers for Direct Access Block Devices

• US 20110072197A1
• Filed: 03/25/2010
• Published: 03/24/2011
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: LSI Corporation (Broadcom, Inc.)
• Inventors: Forhan, Carl, Hicken, Michael, Lund, Timothy
• Granted Patent: US 8,316,178 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/1027 using associative or pseudo-associative address translation means, e.g. translation look-aside buffer [TLB]
• CPC Class Codes: G06F 13/14 Handling requests for interconnection or transfer
• CPC Class Codes: G06F 13/24 using interrupt G06F13/32 takes precedence
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7203 Temporary buffering, e.g. using volatile buffer or dedicated buffer blocks
• CPC Class Codes: G06F 2213/0028 Serial attached SCSI [SAS]
• CPC Class Codes: G06F 3/00 Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements

Abstract

Described embodiments provide a method of transferring, by a media controller, data associated with a host data transfer between a host device and a storage media. A buffer layer module of the media controller segments the host data transfer into one or more data transfer segments. Each data transfer segment corresponds to at least a portion of the data. The buffer layer module allocates a number of physical buffers to a virtual circular buffer for buffering the one or more data transfer segments. The buffer layer module transfers, by the virtual circular buffer, each of the data transfer segments between the host device and the storage media through the allocated physical buffers.

Claims

1. A method of transferring, by a media controller, data associated with a host data transfer between a host device and a storage media, the method comprising:

by a buffer layer module of the media controller;

segmenting the host data transfer into one or more data transfer segments, wherein each data transfer segment corresponds to at least a portion of the data;

allocating a number of physical buffers to a virtual circular buffer for buffering the one or more data transfer segments; and

transferring, by the virtual circular buffer, each of the data transfer segments between the host device and the storage media through the allocated physical buffers.

2. The invention of claim 1, wherein the step of transferring, by the virtual circular buffer, each of the data transfer segments comprises:

if the host data transfer is a host write operation;

a) providing, by a host layer module of the media controller, an initial number of data transfer segments to corresponding ones of the allocated physical buffers, the number of data transfer segments equivalent to the number of allocated physical buffers;

b) providing, by the buffer layer module, the number of data transfer segments to the storage media; and

c) repeating steps a) and b) for each subsequent number of data transfer segments that remain;

otherwise, if the host data transfer is a host read operation;

d) transferring, by the buffer layer module, an initial number of data transfer segments from the storage media to corresponding ones of the allocated physical buffers, the number of data transfer segments equivalent to the number of allocated physical buffers;

e) providing, by the buffer layer module, the number of data transfer segments to the host layer module for transmission to the host device; and

f) repeating steps d) and e) for each subsequent number of data transfer segments that remain.

3. The invention of claim 2, further comprising:

if the host data transfer is a host write operation;

performing, in parallel, i) a media-side transfer of step b) for a first number of data transfer segments, and ii) a host-side transfer of step a) for a second number of data transfer segments;

otherwise, if the host data transfer is a host read operation;

performing, in parallel, i) a host-side transfer of step e) for a first number of data transfer segments, and ii) a media-side transfer of step d) for a second number of data transfer segments.

4. The invention of claim 2, comprising reusing the allocated physical buffers of the virtual circular buffer to buffer each subsequent number of data transfer segments.

5. The invention of claim 2, comprising allocating alternate physical buffers to the virtual circular buffer to buffer each subsequent number of data transfer segments.

6. The invention of claim 1, wherein, for the method, the storage media comprises flash memory, the flash memory comprising one or more flash memory dies, and wherein one or more virtual circular buffers each correspond to one of the one or more flash memory dies.

7. The invention of claim 6, further comprising:

performing, in parallel, one or more host data transfers by the one or more virtual circular buffers, each of the host data transfers between the host device and the one or more flash memory dies transferred through the allocated physical buffers of the one or more virtual circular buffers.

8. The invention of claim 1, wherein the initial number of allocated physical buffers is two.

9. The invention of claim 8, further comprising:

if the media controller has available buffer resources, allocating one or more additional physical buffers to buffer the data transfer segments.

10. The invention of claim 1, wherein the size of the data transfer segments is 256 kB.

11. A machine-readable storage medium, having encoded thereon program code, wherein, when the program code is executed by a machine, the machine implements a method of transferring, by a media controller, data associated with a host data transfer between a host device and a storage media, the method comprising:

by a buffer layer module of the media controller;

segmenting the host data transfer into one or more data transfer segments, wherein each data transfer segment corresponds to at least a portion of the data;

allocating a number of physical buffers to a virtual circular buffer for buffering the one or more data transfer segments; and

transferring, by the virtual circular buffer, each of the data transfer segments between the host device and the storage media through the allocated physical buffers.

12. The invention of claim 11, wherein the step of transferring, by the virtual circular buffer, each of the data transfer segments comprises:

if the host data transfer is a host write operation;

a) providing, by a host layer module of the media controller, an initial number of data transfer segments to corresponding ones of the allocated physical buffers, the number of data transfer segments equivalent to the number of allocated physical buffers;

b) providing, by the buffer layer module, the number of data transfer segments to the storage media; and

c) repeating steps a) and b) for each subsequent number of data transfer segments that remain;

otherwise, if the host data transfer is a host read operation;

d) transferring, by the buffer layer module, an initial number of data transfer segments from the storage media to corresponding ones of the allocated physical buffers, the number of data transfer segments equivalent to the number of allocated physical buffers;

e) providing, by the buffer layer module, the number of data transfer segments to the host layer module for transmission to the host device; and

f) repeating steps d) and e) for each subsequent number of data transfer segments that remain.

13. The invention of claim 12, further comprising:

if the host data transfer is a host write operation;

performing, in parallel, i) a media-side transfer of step b) for a first number of data transfer segments, and ii) a host-side transfer of step a) for a second number of data transfer segments;

otherwise, if the host data transfer is a host read operation;

performing, in parallel, i) a host-side transfer of step e) for a first number of data transfer segments, and ii) a media-side transfer of step d) for a second number of data transfer segments.

14. The invention of claim 12, comprising reusing the allocated physical buffers of the virtual circular buffer to buffer each subsequent number of data transfer segments.

15. The invention of claim 12, comprising allocating alternate physical buffers to the virtual circular buffer to buffer each subsequent number of data transfer segments.

16. The invention of claim 11, wherein, for the method, the storage media comprises flash memory, the flash memory comprising one or more flash memory dies, and wherein one or more virtual circular buffers each correspond to one of the one or more flash memory dies.

17. The invention of claim 16, further comprising:

performing, in parallel, one or more host data transfers by the one or more virtual circular buffers, each of the host data transfers between the host device and the one or more flash memory dies transferred through the allocated physical buffers of the one or more virtual circular buffers.

18. The invention of claim 11, further comprising:

if the media controller has available buffer resources, allocating one or more additional physical buffers to buffer the data transfer segments.

19. A media controller that transfers data associated with a host data transfer between a host device and at least one storage media, the media controller comprising:

a host layer module adapted to process the host data transfer;

a buffer layer module adapted to i) segment the host data transfer into one or more data transfer segments, wherein each data transfer segment corresponds to at least a portion of the data, and ii) allocate one or more physical buffers to a virtual circular buffer;

wherein, if the host data transfer is a host write operation;

the host layer module transfers an initial number of data transfer segments to corresponding ones of an initial number of allocated physical buffers of the virtual circular buffer, the initial number of data transfer segments equivalent to the initial number of allocated physical buffers;

the buffer layer module transfers, in parallel, i) the initial number of data transfer segments to the storage media from the virtual circular buffer, and ii) one or more subsequent numbers of data transfer segments from the host layer module to corresponding ones of allocated physical buffers of the virtual circular buffer for remaining data transfer segments;

otherwise, if the host data transfer is a host read operation;

the buffer layer module transfers an initial number of data transfer segments from the storage media to corresponding ones of the allocated physical buffers of the virtual circular buffer, the initial number of data transfer segments equivalent to the initial number of allocated physical buffers; and

the buffer layer module transfers, in parallel, i) the initial number of data transfer segments from the virtual circular buffer to the host layer module, and ii) one or more subsequent numbers of data transfer segments from storage media to subsequent corresponding ones of allocated physical buffers of the virtual circular buffer for remaining data transfer segments.

20. The invention of claim 19, wherein the apparatus is implemented in a monolithic integrated circuit chip.