Opportunity window hints for background operations in SSD

• US 10,353,628 B2
• Filed: 06/15/2017
• Issued: 07/16/2019
• Est. Priority Date: 04/13/2017
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kachare, Ramdas, Gim, Jongmin, Ki, Yang Seok
• Primary Examiner(s): Cardwell, Eric
• Application Number:
  US15/624,430
• Publication Number:
  US 20180300084A1
• Time in Patent Office: 761 Days
• CPC Class Codes: G06F 11/3034 where the computing system component is a storage system, e.g. DASD based or network based digital input from or digital output to record carriers G06F3/06; digital recording or reproducing G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097
• CPC Class Codes: G06F 11/34 Recording or statistical evaluation of computer activity, e.g. of down time, of input/output operation ; Recording or statistical evaluation of user activity, e.g. usability assessment
• CPC Class Codes: G06F 11/3452 Performance evaluation by statistical analysis
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/10 Address translation
• CPC Class Codes: G06F 2201/81 Threshold
• CPC Class Codes: G06F 2212/7201 Logical to physical mapping or translation of blocks or pages
• CPC Class Codes: G06F 2212/7205 Cleaning, compaction, garbage collection, erase control
• CPC Class Codes: G06F 3/0611 in relation to response time
• CPC Class Codes: G06F 3/0653 Monitoring storage devices or systems
• CPC Class Codes: G06F 3/0659 Command handling arrangements, e.g. command buffers, queues, command scheduling
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

A method includes: receiving a plurality of host commands from a host to access storage media of a solid-state drive (SSD); monitoring a raw rate for performing the plurality of host commands; calculating an average rate by taking an average of the raw rate over a time unit; comparing the average rate against a threshold; detecting that the average rate falls below the threshold indicating an opening of an opportunity window; providing hints for the opportunity window; and determining whether to perform pending or imminent background operations during the opportunity window.

Claims

1. A method comprising:

receiving a plurality of host commands from a host to access storage media of a solid-state drive (SSD);

monitoring a raw rate for performing the plurality of host commands based on an amount of data transferred between the host and the SSD;

calculating an average rate by taking an average of the raw rate over a time unit using a host-programmable weight;

comparing the average rate against a threshold;

detecting that the average rate falls below the threshold indicating an opening of an opportunity window;

providing hints for the opportunity window; and

determining whether to perform pending or imminent background operations during the opportunity window,

wherein the method further comprises;

calculating a plurality of average rates by taking an average of a plurality of raw rates over a time unit;

comparing the plurality of average rates against a set of thresholds;

detecting that a first average rate falls below a first threshold indicating an opening of a first opportunity window;

detecting that a second average rate falls below a second threshold indicating an opening of a second opportunity window;

providing hints for the first and second opportunity windows;

determining whether to perform a first subset of the pending or imminent background operations during the first opportunity window; and

determining whether to perform a second subset of the pending or imminent background operations during the second opportunity window.

2. The method of claim 1, further comprising:

initiating a host command among the plurality of host commands;

posting a completion entry for each of the plurality of host commands; and

updating the average rate after executing each host command.

3. The method of claim 1, wherein the raw rate is a raw host read rate, and the average rate is an average host read rate.

4. The method of claim 1, wherein the raw rate is a raw host write rate, and the average rate is an average host write rate.

5. The method of claim 1,

wherein the host sends a host command to the SSD to program the host-programmable weight.

6. The method of claim 1, wherein a host interface layer of the SSD provides the hints indicating that the opportunity window is available to a flash translation layer (FTL) of the SSD.

7. The method of claim 1, wherein the background operations include one or more of updating an FTL mapping table to the flash media, saving a table for program/erase (P/E) counts per block and various logs to the flash media, write cache offloading, and recycling flash blocks/pages, and garbage collection.

8. The method of claim 1, the threshold is determined based on one or more of an application running on the host, a type of the SSD, characteristics of the host commands.

9. The method of claim 1, further comprising:

detecting that the average rate crosses over the threshold indicating a closure of the opportunity window; and

halting or scaling down active background operations.

10. The method of claim 1, further comprising:

programming one or more parameters for calculating the average rate using commands received from the host.

11. A solid-state drive (SSD) comprising:

a flash media; and

a controller comprising a host interface layer, a flash translation layer, and a flash interface layer,

wherein the host interface layer is configured to;

receive a plurality of host commands from a host to access storage media of a solid-state drive (SSD);

monitor a raw rate for performing the plurality of host commands based on an amount of data transferred between the host and the SSD;

calculate an average rate by taking an average of the raw rate over a time unit using a host-programmable weight;

compare the average rate against a threshold;

detect that the average rate falls below the threshold indicating an opening of an opportunity window; and

provide hints for the opportunity window to the flash translation layer,

wherein the flash translation layer is configured to determine whether to perform pending or imminent background operations during the opportunity window, and

wherein the flash interface layer is configured to perform data transfer to and from the flash media in accordance with the plurality of host commands,

wherein the host interface layer is further configured to;

calculate a plurality of average rates by taking an average of a plurality of raw rates over a time unit;

compare the plurality of average rates against a set of thresholds;

detect that a first average rate falls below a first threshold indicating an opening of a first opportunity window;

detect that a second average rate falls below a second threshold indicating an opening of a second opportunity window;

provide hints for the first and second opportunity windows;

determine whether to perform a first subset of the pending or imminent background operations during the first opportunity window; and

determine whether to perform a second subset of the pending or imminent background operations during the second opportunity window.

12. The SSD of claim 11, wherein the host interface layer is further configured to:

initiate a host command among the plurality of host commands;

post a completion entry for each of the plurality of host commands; and

update the average rate after executing each host command.

13. The SSD of claim 11, wherein the raw rate is a raw host read rate, and the average rate is an average host read rate.

14. The SSD of claim 11, wherein the raw rate is a raw host write rate, and the average rate is an average host write rate.

15. The SSD of claim 11, wherein the background operations include one or more of updating an FTL mapping table to the flash media, saving a table for program/erase (P/E) counts per block and various logs to the flash media, write cache offloading, and recycling flash blocks/pages, and garbage collection.

16. The SSD of claim 11, wherein the host sends a host command to the SSD to program the host-programmable weight.

17. The SSD of claim 11, wherein the threshold is determined based on one or more of an application running on the host, a type of the SSD, characteristics of the host commands.

18. The SSD of claim 11, wherein the host interface layer is further configured to detect that the average rate crosses over the threshold indicating a closure of the opportunity window, and wherein the flash translation layer is further configured to halt or scale down active background operations.

19. The SSD of claim 11, wherein one or more parameters for calculating the average rate are programmed using commands received from the host.

20. The SSD of claim 11, wherein the SSD is compatible with the non-volatile memory express (NVMe) standard of the NVMe over Fabrics (NVMe-oF) standard.