System and method for adaptively optimized refresh of memory
First Claim
1. A system for adaptive refresh of a memory device having multiple integrated circuit chips, the system comprising:
- a command generation portion executable to generate commands for actuating a plurality of operational tasks on the memory device, the operational tasks including at least read, write, and refresh operations for selectively addressed storage cells of the memory device, each chip of the memory device defining a plurality of banks, the storage cells of each bank being organized in a plurality of individually accessible pages;
a command management portion coupled to said command generation portion, said command management portion including;
a command queue unit storing the commands for operational tasks on the memory device awaiting execution; and
,an execution strategy unit coupled to said command queue unit for selecting the commands stored in said command queue unit for timely execution of corresponding operational tasks on the memory device; and
,a refresh management portion coupled to said command generation and command management portions for scheduling actuation of a plurality of refresh operations to be adaptively interleaved with other operational tasks, wherein full recursive refresh of the storage cells is carried out for the memory device within a predetermined refresh window of time, said refresh management portion including;
a chip refresh unit executable to selectively actuate each refresh operation for a chip-based selection of storage cells, a refresh request for a selected chip actuating a series of refresh operations to collectively refresh the storage cells of the selected chip, whereby for each refresh request for a selected chip the storage cells in all banks of the selected chip are collectively refreshed by the series of refresh operations exclusive of actuation of other operational tasks directed to the selected chip, anda bank refresh unit executable to selectively actuate each refresh operation for a bank-based selection of storage cells, whereby the storage cells in a selected bank are refreshed, the bank refresh unit having an enable/disable input controllable by the chip refresh unit, whereby the chip refresh unit can enable and disable the bank refresh unit to adaptively adjust the granularity of the refresh operation of the memory device according to three zones of operation, the zones including;
a first zone in which the bank refresh unit is enabled and a memory-chip-based auto refresh is disabled,a second zone in which the bank refresh unit is disabled and the memory-chip-based auto refresh is enabled, anda third zone in which the bank refresh unit is enabled and a memory-chip-based auto refresh is enabled only upon determination that the bank refresh unit is unable to refresh the bank-based selection of storage cells within a required refresh time,wherein the memory-chip-based auto refresh is executed by the chip refresh unit to maintain the refresh request count relative to an average periodic refresh interval time parameter and refresh time debit/credit information associated therewith for the chip-based selection of storage cells.
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Accused Products
Abstract
A system and method are provided for system for adaptive refresh of a memory device having multiple integrated circuit chips. A command generation portion generates commands for actuating a plurality of operational tasks on the memory device, including at least read, write, and refresh operations for selectively addressed storage cells of the memory device. A command management portion stores the commands and selects from the commands for timely execution of corresponding operational tasks on the memory device. A refresh management portion coupled to the command generation and command management portions actuates a plurality of refresh operations adaptively interleaved with other operational tasks, such that recursive refresh of the storage cells is carried out for the memory device within a predetermined refresh window of time. The refresh management portion selectively actuates each refresh operation for a chip-based selection of storage cells, whereby the storage cells of a selected chip are refreshed.
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Citations
20 Claims
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1. A system for adaptive refresh of a memory device having multiple integrated circuit chips, the system comprising:
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a command generation portion executable to generate commands for actuating a plurality of operational tasks on the memory device, the operational tasks including at least read, write, and refresh operations for selectively addressed storage cells of the memory device, each chip of the memory device defining a plurality of banks, the storage cells of each bank being organized in a plurality of individually accessible pages; a command management portion coupled to said command generation portion, said command management portion including; a command queue unit storing the commands for operational tasks on the memory device awaiting execution; and
,an execution strategy unit coupled to said command queue unit for selecting the commands stored in said command queue unit for timely execution of corresponding operational tasks on the memory device; and
,a refresh management portion coupled to said command generation and command management portions for scheduling actuation of a plurality of refresh operations to be adaptively interleaved with other operational tasks, wherein full recursive refresh of the storage cells is carried out for the memory device within a predetermined refresh window of time, said refresh management portion including; a chip refresh unit executable to selectively actuate each refresh operation for a chip-based selection of storage cells, a refresh request for a selected chip actuating a series of refresh operations to collectively refresh the storage cells of the selected chip, whereby for each refresh request for a selected chip the storage cells in all banks of the selected chip are collectively refreshed by the series of refresh operations exclusive of actuation of other operational tasks directed to the selected chip, and a bank refresh unit executable to selectively actuate each refresh operation for a bank-based selection of storage cells, whereby the storage cells in a selected bank are refreshed, the bank refresh unit having an enable/disable input controllable by the chip refresh unit, whereby the chip refresh unit can enable and disable the bank refresh unit to adaptively adjust the granularity of the refresh operation of the memory device according to three zones of operation, the zones including; a first zone in which the bank refresh unit is enabled and a memory-chip-based auto refresh is disabled, a second zone in which the bank refresh unit is disabled and the memory-chip-based auto refresh is enabled, and a third zone in which the bank refresh unit is enabled and a memory-chip-based auto refresh is enabled only upon determination that the bank refresh unit is unable to refresh the bank-based selection of storage cells within a required refresh time, wherein the memory-chip-based auto refresh is executed by the chip refresh unit to maintain the refresh request count relative to an average periodic refresh interval time parameter and refresh time debit/credit information associated therewith for the chip-based selection of storage cells. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for adaptive refresh of a memory device having multiple integrated circuit chips, the method comprising:
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defining a plurality of banks in each chip of the memory device, each bank being organized into a plurality of individually accessible pages, each page formed by a plurality of storage cells; executing a command generation portion implemented in a processor to generate commands for actuating a plurality of operational tasks on the memory device, the operational tasks including at least read, write, and refresh operations for selectively addressed storage cells of the memory device; executing command management on a command management portion implemented in a processor, said command management including; storing the commands for operational tasks on the memory device in a computer readable command queue unit to await execution; and
,actuating an execution strategy unit coupled to said command queue unit to select the commands stored in said command queue unit for timely execution of corresponding operational tasks on the memory device; and
,executing refresh management on a refresh management portion implemented in a processor for scheduling actuation of a plurality of refresh operations to be adaptively interleaved with other operational tasks, wherein full recursive refresh of the storage cells is carried out for the memory device within a predetermined refresh window of time, said refresh management including a per-chip refresh executable to selectively actuate each refresh operation for a chip-based selection of storage cells, a refresh request for a selected chip actuating a series of refresh operations to collectively refresh the storage cells of the selected chip or bank(s), whereby for each refresh request for a selected chip, the storage cells in all banks of the selected chip are collectively refreshed by the series of refresh operations exclusive of actuation of other operational tasks directed to the selected chip, and said refresh management further including a bank refresh executable to selectively actuate each refresh operation for a bank-based selection of storage cells, whereby the storage cells in a selected bank are refreshed, the bank refresh being enablable/disableable to enable or disable the bank refresh to adaptively adjust the granularity of the refresh operation of the memory device according to three zones of operation, the zones including; a first zone in which the bank refresh is enabled and a memory-chip-based auto refresh is disabled, a second zone in which the bank refresh is disabled and the memory-chip-based auto refresh is enabled, and a third zone in which the bank refresh is enabled and a memory-chip-based auto refresh is enabled only upon determination that the bank refresh unit is unable to refresh the bank-based selection of storage cells within a required refresh time, wherein, when the memory-chip-based auto refresh is enabled, the per-chip refresh includes the memory-chip-based auto refresh to maintain the refresh request count relative to an average periodic refresh interval time parameter and refresh time debit/credit information associated therewith for the chip-based selection of storage cells. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A system for adaptive refresh of a memory device having multiple integrated circuit chips with selective granularity of refresh, the system comprising:
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a command generation portion executable to generate commands for actuating a plurality of operational tasks on the memory device, the operational tasks including at least read, write, and refresh operations for selectively addressed storage cells of the memory device, each chip of the memory device defining at least one logical rank containing a plurality of banks, each bank being organized into a plurality of individually accessible pages, each page formed by at least one row of storage cells; a command management portion coupled to said command generation portion, said command management portion including; a command queue unit storing the commands for operational tasks on the memory device awaiting execution; and
,an execution strategy unit coupled to said command queue unit for selecting the commands stored in said command queue unit for timely execution of corresponding operational tasks on the memory device; and
,a refresh management portion coupled to said command generation and command management portions for scheduling actuation of a plurality of refresh operations to be adaptively interleaved with other operational tasks, wherein full recursive refresh of the storage cells is carried out for the memory device within a predetermined refresh window of time, said refresh management portion including; a bank refresh unit executable to selectively actuate each refresh operation for a bank-based selection of storage cells, whereby the storage cells in a selected bank are refreshed, the bank refresh unit having an enable/disable input, whereby the bank refresh unit can be enabled or disabled to adaptively adjust the granularity of the refresh operation of the memory device according to three zones of operation, the zones including; a first zone in which the bank refresh unit is enabled and a memory-chip-based auto refresh is disabled, a second zone in which the bank refresh unit is disabled and the memory-chip-based auto refresh is enabled, and a third zone in which the bank refresh unit is enabled and a memory-chip-based auto refresh is enabled only upon determination that the bank refresh unit is unable to refresh the bank-based selection of storage cells within a required refresh time, wherein the memory-chip-based auto refresh is executed to maintain the refresh request count relative to an average periodic refresh interval time parameter and refresh time debit/credit information associated therewith for the chip-based selection of storage cells; and
,a rank refresh unit executable to selectively actuate each refresh operation for a rank-based selection of storage cells, a refresh request for a selected rank actuating a series of refresh operations to collectively refresh the storage cells of the selected rank, whereby, for each refresh request for a selected rank, the storage cells in all banks of the selected rank are collectively refreshed by the series of refresh operations exclusive of actuation, between individual refresh operations in the series for the selected rank, of other operational tasks directed to the selected rank and at least one rank other than the selected rank is scheduled to undergo at least one active operational task between individual refresh operations in the series for the selected rank, said rank refresh unit including; a refresh monitoring section for each selectable rank of the memory device, said refresh monitoring section maintaining a refresh deferral history for the selectable rank within the predetermined refresh window; and
,a refresh control section coupled to each said refresh monitoring section of each selectable rank, said refresh control section generating a refresh request for at least one of the selectable ranks responsive to the refresh deferral histories and activity states of the selectable ranks with respect to execution of an operational task thereon within a predefined period of pendency. - View Dependent Claims (19, 20)
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Specification