Method and circuit for protecting a DRAM memory device from the row hammer effect
AssigneeUpmem
InventorsFabrice Devaux, Renaud Ayrignac
Life of this patent
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Abstract
A method of protecting a DRAM memory device from the row hammer effect, the memory device comprising a plurality of banks composed of memory rows, may be implemented by at least one logic prevention device configured to respectively associate contiguous sections of rows of a bank with sub-banks. The prevention logic is also configured to execute a preventive refresh cycle of the sub-banks that is entirely executed before the number of rows activated in a sub-bank exceed a critical hammer value. A DRAM memory device, a buffer circuit or a controller of such a memory may comprise the logic for preventing the row hammer effect.
Claims31
A method of protecting a DRAM memory device from the row hammer effect, the memory device comprising a plurality of banks composed of memory rows, the method being implemented by at least one prevention logic configured to respectively define sub-banks dividing each bank as contiguous sections of rows, the prevention logic being configured to execute, at each activation of a row of a given sub-bank, a step of incrementing an activation counter associated with the given sub-bank and being configured to execute a preventive refresh sequence comprising:
- a step of identifying a need for preventive refresh of a determined sub-bank of the sub-banks of the memory device;
- a step of triggering an operation to refresh a current row designated by a current row index associated with the determined sub-bank;
- a step of incrementing the current row index associated with the determined sub-bank;
- wherein the preventive refresh sequence is forming a percentage of progress of a preventive refresh cycle, the preventive refresh cycle leading to refresh at least all the rows of the determined sub-bank, and wherein the preventive refresh cycle of the determined sub-bank is entirely executed before the number of rows activated in the determined sub-bank exceed a critical hammer value.
A method of protecting a DRAM memory device from the row hammer effect, the memory device comprising a plurality of banks composed of memory rows, the method being implemented by at least one prevention logic configured to respectively define sub-banks as contiguous sections of rows of a bank, the prevention logic being configured to execute a preventive refresh sequence comprising:
- a step of identifying a need for preventive refresh of a determined sub-bank of the sub-banks of the memory device;
- a step of triggering an operation to refresh a current row designated by a current row index associated with the determined sub-bank;
- a step of incrementing the current row index associated with the determined sub-bank;
- wherein the preventive refresh sequence is forming a step of a preventive refresh cycle leading to refresh at least all the rows of the determined sub-bank, and wherein the preventive refresh cycle of the determined sub-bank is entirely executed before the number of rows activated in the determined sub-bank exceed a critical hammer value,
- wherein each sub-bank is associated with an activation threshold, and the prevention logic is configured to execute, at each activation of a row of a given sub-bank of the sub-banks of the memory device, a step of incrementing an activation counter associated with the given sub-bank and to determine a required number of preventive refreshes of the given sub-bank, and in which the required number of preventive refreshes of each given sub-bank is stored in a data structure.
A method of protecting a DRAM memory device from the row hammer effect, the memory device comprising a plurality of banks composed of memory rows, the method being implemented by at least one prevention logic configured to respectively define sub-banks as contiguous sections of rows of a bank, the prevention logic being configured to execute a preventive refresh sequence comprising:
- a step of identifying a need from preventive refresh of a determined sub-bank of the sub-bank of the memory device;
- a step of triggering an operation to refresh a current row designated by a current row index associated with the determined sub-bank;
- a step of incrementing the current row index associated with the determined sub-bank;
- wherein the preventive refresh sequence is forming a step of preventive refresh cycle leading to refresh at least all the rows of the determined sub-bank, and wherein the preventive refresh cycle of the determined sub-bank is entirely executed before the number of rows activated in the determined sub-bank exceed a critical hammer value,
- wherein each sub-bank associated with an activation threshold, and the prevention logic is configured to execute, at each activation of a row of a given sub-bank of the sub-banks of the memory device, a step of incrementing an activation counter associated with the given sub-bank and to determine a required number of preventive refreshes of the given sub-banks, and in which the activation threshold defines a variable progress coefficient during a complete cycle of preventive refresh of the determined sub-bank.
Dependencies are inferred from the claim text.