Non volatile mass storage device with improved refresh algorithm
A refreshing method is described. The method includes recognizing a set of blocks of a non-volatile memory for refreshing and then refreshing a subset of the data within the blocks, where, invalid data within the blocks is not recognized for refreshing and a group of blocks whose oldest data has not aged for a pre-set time period is not recognized for refreshing.
1. An apparatus, comprising:
a controller to implement a non-volatile memory refresh algorithm, the controller comprising logic circuitry to recognize a set of blocks of the non-volatile memory for refreshing and then refresh only a subset of data stored within the set of blocks, where, invalid data is not recognized for refreshing and a group of blocks whose oldest data has not aged for a pre-set time period is not recognized for refreshing.
2. The apparatus of claim 1 wherein blocks of a same band are grouped together for recognition of refreshing and wherein valid data of the blocks within the same band are refreshed over time as a unit.
3. The apparatus of claim 2 wherein a next band's blocks do not begin to be refreshed until a previous band's blocks have been fully refreshed.
4. The apparatus of claim 1 wherein data invalidity/validity is tracked at a granularity that is less than or equal to a block.
5. The apparatus of claim 1 wherein the pre-set time period is programmable.
6. The apparatus of claim 1 wherein the non-volatile memory refresh algorithm determines a refresh rate as an amount of valid data recognized for refresh normalized by an expiration time less the pre-set time period.
7. The apparatus of claim 6 wherein the non-volatile memory refresh algorithm determines respective refresh rates for multiple bands having blocks recognized for refresh and combines the respective refresh rates to determine a refresh rate to be applied to a particular one of the multiple bands.
8. The apparatus of claim 1 wherein the controller is to persist, as part of a power down process of a non-volatile mass storage device, any of:
a hold-off period;
a maximum permitted time window without refresh; and,
timer values for different groups of blocks.
9. The apparatus of claim 1 wherein more than one group of blocks whose ageing is tracked as a single unit are concurrently refreshed.
10. A computing system, comprising:
a plurality of processing cores;
a system memory;
a memory controller disposed between the system memory and the plurality of processing cores;
a peripheral controller coupled to the memory controller;
a non volatile mass storage device comprising a controller to implement a non-volatile memory refresh algorithm, the controller comprising logic circuitry to recognize a set of blocks of the non-volatile memory for refreshing and then refresh only a subset of data stored within the set of blocks, where, invalid data is not recognized for refreshing and a group of blocks whose oldest data has not aged for a pre-set time period is not recognized for refreshing.
11. The computing system of claim 10 wherein blocks of a same band are grouped together for recognition of refreshing and wherein valid data of the blocks within the same band are refreshed over time as a unit.
12. The computing system of claim 11 wherein a next band's blocks do not begin to be refreshed until a previous band's blocks have been fully refreshed.
13. The computing system of claim 10 wherein data invalidity/validity is tracked at a granularity that is less than or equal to a block.
14. The computing system of claim 10 wherein the pre-set time period is programmable.
15. The computing system of claim 10 wherein the non-volatile memory refresh algorithm determines a refresh rate as an amount of valid data recognized for refresh normalized by an expiration time less the pre-set time period.
16. A machine readable medium having stored thereon instructions that when processed by a processor causes a refresh method to be performed, the refresh method comprising:
recognizing a set of blocks of a non-volatile memory for refreshing and then refreshing a subset of data within the set of blocks, where, invalid data within the set of blocks is not recognized for refreshing and a group of blocks whose oldest data has not aged for a pre-set time period is not recognized for refreshing.
17. The machine readable medium of claim 16 further comprising grouping blocks of a same band together for recognition of refreshing and refreshing valid data within the blocks of the same band over time as a unit.
18. The machine readable medium of claim 17 further comprising not beginning to refresh a next band's blocks until a previous band's blocks have been fully refreshed.
19. The machine readable medium of claim 16 wherein the method further comprises persisting, as part of a power down process of a non-volatile mass storage device, any of:
a hold-off period;
a maximum permitted time window without refresh; and,
timer values for different groups of blocks.
20. The machine readable medium of claim 16 wherein the pre-set time period is programmable.
21. The machine readable medium of claim 16 wherein the method further comprises determining a refresh rate as a number of blocks recognized for refresh normalized by an expiration time less the pre-set time period.
22. The machine readable medium of claim 16 wherein more than one group of blocks whose ageing is tracked as a single unit are concurrently refreshed.