Heuristics for selecting subsegments for entry in and entry out operations in an error cache system with coarse and fine grain segments
A memory device comprises a memory bank comprising a plurality of addressable memory cells, wherein the memory bank is divided into a plurality of segments. Further, the device comprises a cache memory operable for storing a second plurality of data words, wherein each data word of the second plurality of data words is either awaiting write verification associated with the memory bank or is to be re-written into the memory bank. The cache memory is divided into a plurality of primary segments, wherein each primary segment of the cache memory is direct mapped to a corresponding segment of the plurality of segments, wherein each primary segment is sub-divided into a plurality of secondary segments, and wherein each of the plurality of secondary segments comprises at least one counter for tracking a number of entries stored therein.
1. A memory device comprising:
a memory bank comprising a plurality of addressable memory cells, wherein the memory bank is divided into a plurality of segments;
a pipeline configured to process write operations of a first plurality of data words addressed to the memory bank;
a cache memory operable for storing a second plurality of data words and associated memory addresses, wherein the second plurality of data words are a subset of the first plurality of data words, wherein the cache memory is associated with the memory bank and wherein further each data word of the second plurality of data words is either awaiting write verification associated with the memory bank or is to be re-written into the memory bank, wherein the cache memory is divided into a plurality of primary segments, wherein each primary segment of the cache memory is direct mapped to a corresponding segment of the plurality of segments of the memory bank, wherein each primary segment of the plurality of primary segments of the cache memory is sub-divided into a plurality of secondary segments, and wherein each of the plurality of secondary segments comprises at least one counter for tracking a number of entries stored therein; and
a logic module operable to:
determine a first primary segment of the plurality of primary segments of the cache memory for performing an access operation; and
select a first secondary segment from the plurality of secondary segments within the first primary segment for performing the access operation, wherein the first secondary segment is selected based on a value of a counter of the selected secondary segment.
2. The memory device of claim 1 , wherein the access operation is an entry-in operation into the first secondary segment, wherein the value of the counter of the first secondary segment is lower than corresponding counter values of other secondary segments within the first primary segment.
3. The memory device of claim 1 , wherein the access operation is an entry-out operation for removing an entry from the first secondary segment, wherein the value of the counter of the first secondary segment is higher than corresponding counter values of other secondary segments within the first primary segment.
4. The memory device of claim 3 , wherein the entry-out operation is incident to a verify operation.
5. The memory device of claim 3 , wherein the entry-out operation is incident to a re-write operation.
6. The memory device of claim 1 , wherein to determine the first primary segment of the plurality of primary segments of the cache memory for performing the access operation, the logic module is further operable to:
determine the first primary segment in the cache memory based on an address of a data word associated with the access operation, wherein the first primary segment directly maps to a segment of the memory bank associated with the access operation.
7. The memory device of claim 1 , wherein each of the plurality of secondary segments of the cache memory is associated with two respective counters to keep track of a number of valid entries corresponding to write 1 errors and a number of valid entries corresponding to write 0 errors stored therein.
8. A memory device comprising:
a plurality of memory banks comprising a plurality of addressable memory cells, wherein each of the plurality of memory banks is divided into a plurality of segments;
a pipeline configured to process write operations of a first plurality of data words addressed to the plurality of memory banks;
a cache memory operable for storing a second plurality of data words and associated memory addresses, wherein the second plurality of data words are a subset of the first plurality of data words, wherein the cache memory is associated with the plurality of memory banks and wherein further each data word of the second plurality of data words is either awaiting write verification associated with a memory bank from the plurality of memory banks or is to be re-written into a memory bank from the plurality of memory banks, wherein the cache memory is divided into a plurality of primary segments, wherein each primary segment of the cache memory is direct mapped to a corresponding segment of the plurality of segments of the memory bank, wherein each primary segment of the plurality of primary segments of the cache memory is sub-divided into a plurality of secondary segments, and wherein each of the plurality of secondary segments comprises at least one counter for tracking a number of entries in stored therein; and
a logic module operable to:
determine a first primary segment of the plurality of primary segments of the cache memory for performing an access operation; and
select a first secondary segment from the plurality of secondary segments within the first primary segment for performing the access operation, wherein the first secondary segment is selected based on a value of a counter of the selected secondary segment.
9. The memory device of claim 8 , wherein the access operation is an entry-in operation into the first secondary segment, wherein the value of the counter of the first secondary segment is lower than corresponding counter values of other secondary segments within the first primary segment.
10. The memory device of claim 8 , wherein the access operation is an entry-out operation for removing an entry from the first secondary segment, wherein the value of the counter of the first secondary segment is higher than corresponding counter values of other secondary segments within the first primary segment.
11. The memory device of claim 10 , wherein the entry-out operation is a verify operation.
12. The memory device of claim 10 , wherein the entry-out operation is a re-write operation.
13. The memory device of claim 8 , wherein to determine the primary segment of the plurality of primary segments of the cache memory for performing the access operation, the logic module is further operable to:
determine the first primary segment in the cache memory based on an address of a data word associated with the access operation, wherein the first primary segment directly maps to a segment of the memory bank associated with the access operation.
14. The memory device of claim 8 , wherein each of the plurality of secondary segments of the cache memory is associated with two respective counters to track of a number of valid entries corresponding to write 1 errors and a number of valid entries corresponding to write 0 errors stored therewithin.
15. A memory device comprising:
a memory bank comprising a plurality of addressable memory cells, wherein the memory bank is divided into a plurality of segments;
a pipeline configured to process write operations of a first plurality of data words addressed to the memory bank;
a cache memory operable for storing a second plurality of data words and associated memory addresses, wherein the second plurality of data words are a subset of the first plurality of data words, wherein the cache memory is associated with the memory bank and wherein further each data word of the second plurality of data words is either awaiting write verification associated with the memory bank or is to be re-written into the memory bank, wherein the cache memory is divided into a plurality of primary segments, wherein each primary segment of the cache memory is direct mapped to a corresponding segment of the plurality of segments of the memory bank, wherein each primary segment of the plurality of primary segments of the cache memory is sub-divided into a plurality of secondary segments, and wherein each of the plurality of secondary segments comprises at least one counter for tracking a number of entries stored therein; and
a logic module operable to:
determine a first primary segment of the plurality of primary segments of the cache memory for performing an access operation; and
select a first secondary segment from the plurality of secondary segments within the first primary segment for performing the access operation based on an address space that the first secondary segment maps to in the memory bank.