Power-efficient monitoring for usage-based-disturbance mitigation
Apparatuses and techniques are described implementing power-efficient monitoring for usage-based-disturbance mitigation. In a first aspect, a memory device takes a less strict approach for monitoring worse-case conditions associated with usage-based disturbance. In particular, the memory device conserves power by foregoing updating a list of rows associated with worse-case conditions until an unlisted row has a substantially worse condition than any one of the listed rows. This decreases how often the memory device expends power to update the list. In an optional second aspect, the memory device performs a partial bit-width comparison operation to evaluate the “substantially worse” criterion. The partial bit-width comparison enables a comparator to be implemented with a smaller footprint and operate with less power as compared to a comparator that is capable of performing a full bit-width comparison operation.
1 . A method performed by a memory device, the method comprising:
storing, within a queue of the memory device, information corresponding to a first row of a memory array, the first row having an activation count that meets a condition for mitigating usage-based disturbance;
comparing a first set of most-significant bits corresponding to the activation count of the first row to a second set of most-significant bits corresponding to an activation count of a second row of the memory array, the first set and the second set having a same quantity of bits;
determining, based on the comparing, that the activation count of the second row is greater than the activation count of the first row by at least a threshold; and
responsive to the determining, updating the queue to store information corresponding to the second row instead of the information corresponding to the first row.
2 . The method of claim 1 , wherein:
the storing of the information corresponding to the first row comprises storing the activation count of the first row; and
the determining that the activation count of the second row is greater than the activation count of the first row by at least the threshold comprises determining that the activation count of the second row is greater than a summation of the activation count of the first row and the threshold.
3 . The method of claim 2 , wherein a value of the threshold is equal to a power of two.
4 . The method of claim 3 , wherein the value of the threshold is greater than or equal to 32.
5 . The method of claim 4 , wherein the value of the threshold is greater than or equal to 64.
6 . The method of claim 3 , wherein the determining that the activation count of the second row is greater than the activation count of the first row by at least a threshold comprises performing a partial bit-width comparison between the activation count of the first row and the activation count of the second row.
7 . The method of claim 1 , further comprising:
performing, based on the queue storing the information corresponding to the second row, one or more refresh operations to mitigate the usage-based disturbance associated with activation of the second row.
8 . The method of claim 1 , wherein:
the activation count of the first row and the activation count of the second row each comprise a first quantity of bits;
the first set of most-significant bits and the second set of most-significant bits each comprise a second quantity of bits; and
a value of the threshold is determined based on a difference between the first quantity of bits and the second quantity of bits.
9 . The method of claim 2 , further comprising:
determining that an activation count of a third row of the memory array is not greater than the activation count of the second row by at least the threshold; and
responsive to the determining that the activation count of the third row is not greater than the activation count of the second row by at least the threshold, continue storing, within the queue, the information corresponding to the second row.
10 . The method of claim 9 , wherein the determining that the activation count of the third row is not greater than the activation count of the second row by at least the threshold comprises one of the following:
determining that the activation count of the third row is less than a summation of the activation count of the second row and the threshold; or
determining that a third set of most-significant bits corresponding to the activation count of the third row is less than a second set of most-significant bits corresponding to the activation count of the second row.
11 . A memory device comprising:
a memory array comprising a first row and a second row;
a queue configured to store information corresponding to the first row, the first row having an activation count that meets a condition for mitigating usage-based disturbance; and
a circuit configured to:
compare a first set of most-significant bits corresponding to the activation count of the first row to a second set of most-significant bits corresponding to an activation count of the second row, the first set and the second set having a same quantity of bits;
determine, based on the comparison, that the activation count of the second row is greater than the activation count of the first row by at least a threshold; and
responsive to the determination, cause the queue to store information corresponding to the second row instead of the information corresponding to the first row.
12 . The memory device of claim 11 , wherein the circuit comprises a comparator configured to determine that the activation count of the second row is greater than a summation of the activation count of the first row and the threshold.
13 . The memory device of claim 11 , wherein a value of the threshold is equal to a power of two.
14 . The memory device of claim 11 , wherein the circuit is configured to:
cause, based on the queue storing the information corresponding to the second row, the memory device to perform one or more refresh operations to mitigate the usage-based disturbance associated with activation of the second row.
15 . The memory device of claim 11 , wherein:
the memory array comprises a third row; and
the circuit is configured to:
determine that an activation count of the third row is not greater than the activation count of the second row by at least the threshold; and
responsive to the determination that the activation count of the third row is not greater than the activation count of the second row by at least the threshold, cause the queue to continue storing the information corresponding to the second row.
16 . The memory device of claim 15 , wherein the circuit is configured to determine that the activation count of the third row is not greater than the activation count of the second row by at least the threshold based on one of the following:
a determination that the activation count of the third row is less than a summation of the activation count of the second row and the threshold; or
a determination that a third set of most-significant bits corresponding to the activation count of the third row is less than a second set of most-significant bits corresponding to the activation count of the second row.
17 . A memory device comprising:
a queue configured to store, within an entry of the queue, an activation count of a first row and an address of the first row, the activation count meeting a condition for mitigating usage-based disturbance; and
a comparator coupled to the queue and configured to:
compare a first set of most-significant bits corresponding to the activation count of the first row to a second set of most-significant bits corresponding to an activation count of an active row, the first set and the second set having a same quantity of bits; and
responsive to the comparison indicating the activation count of the active row is greater than the activation count of the first row by at least a threshold, cause the queue to update the entry to store the activation count of the active row and an address of the active row; or
responsive to the comparison indicating the activation count of the active row is not greater than the activation count of the first row by at least the threshold, cause the queue to continue storing the activation count and the address of the first row.
18 . The memory device of claim 17 , wherein the comparator is configured to determine that the activation count of the active row is greater than a summation of the activation count of the first row and the threshold.
19 . The memory device of claim 18 , wherein a value of the threshold is equal to a power of two.
20 . The memory device of claim 17 , wherein the memory device is configured to:
perform, based on the queue storing the activation count of the active row, one or more refresh operations to mitigate the usage-based disturbance associated with activation of the active row; or
perform, based on the queue storing the activation count of the first row, one or more other refresh operations to mitigate the usage-based disturbance associated with activation of the first row.