1. A method for monitoring and controlling repetitive accesses to a volatile memory, the volatile memory comprising at least one bank including a plurality of rows of cells, the method comprising:
mapping each row to one of a plurality of logical blocks;
managing a counter for each of the logical blocks, wherein each counter increases when any row mapped to a particular logical block is accessed within a monitoring window, wherein the monitoring window comprises a time period that is less than a refresh interval of the volatile memory;
selectively throttling access to rows mapped to a first one of the logical blocks when the counter associated with the first logical block exceeds a threshold to prevent row hammering.
2. The method of claim 1, wherein the mapping comprises applying a pseudo-random hash-based mapping algorithm to the volatile memory.
3. The method of claim 1, wherein the monitoring window is a fixed time window.
4. The method of claim 1, wherein the monitoring window is a rolling time window.
5. The method of claim 1, wherein the threshold is based on the refresh interval, a maximum access count of the volatile memory, and the monitoring window.
6. The method of claim 1, wherein the threshold is derived based on the following equation:
T
=
floor
(
A
2
tREF
*
W
)
where T is the threshold, A is a maximum number of activates, tREF is the refresh interval, and W is the monitoring window.
7. The method of claim 1, wherein the threshold is derived based on the following equation:
T
=
floor
(
A
2
K
+
1
)
where T is the threshold, A is a maximum number of activates, and K is defined as:
K
=
ceiling
(
tREF
W
)
and where tREF is the refresh interval.
8. The method of claim 1, wherein the selective throttling comprises:
preventing any further activates of any row mapped to the first logical block within the monitoring window.
9. The method of claim 1, further comprising:
enforcing a gap between consecutive activates to rows in the first block, until an end of the monitoring window by preventing activates to rows in the first block when the counter associated with the first block exceeds a fraction of the threshold, wherein the gap is inversely proportional to the fraction.
10. The method of claim 1, further comprising:
determining a source of row activates;
wherein the selective throttling comprises instructing the source to temporarily cease requests to access the volatile memory.
11. A system comprising:
a volatile memory comprising at least one bank comprising a plurality of rows; and
a memory controller coupled to the volatile memory, the memory controller operative to:
map each of the plurality of rows to one of a plurality of logical blocks;
define a monitoring window;
maintain counters for each of the logical blocks, wherein a counter is incremented anytime a row associated with a logical block is accessed within the monitoring window;
determine whether any one of the counters exceeds a threshold; and
limit activates to rows associated with any of the logical blocks having counters that exceed the threshold.
12. The system of claim 11, wherein the monitoring window is a fixed window.
13. The system of claim 11, wherein the monitoring window is a rolling window.
14. The system of claim 11, wherein the threshold is based on a refresh interval of the volatile memory, a maximum access count of the volatile memory, and the monitoring window.
15. The system of claim 14, wherein the refresh interval is substantially the same as a refresh interval obtained from a specification of the volatile memory.
16. The system of claim 14, wherein the refresh interval is greater than a refresh interval obtained from a specification of the volatile memory.
17. The system of claim 14, wherein the controller is operative to map the rows to a first number of logical blocks based on the refresh interval.
18. The system of claim 11, further comprising:
a plurality of components other than the controller and the volatile memory that access the volatile memory, wherein the controller is further operative to:
instruct at least one the components to at least temporarily cease accessing the volatile memory when that at least one component is responsible for cause at least one or more counters to exceed the threshold.
19. The system of claim 11, further comprising:
at least one component that functions as a realtime agent; and
at least one component that functions as a non-realtime agent,
wherein the controller is operative to:
determine if one of the at least one component that functions as a non-realtime component is responsible for volatile memory accesses that causes one of the counters to exceed the threshold;
instruct that component to at least temporarily cease accessing the volatile memory.
20. The system of claim 11, wherein the volatile memory is dynamic random access random access memory.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A refrigerant composition which comprises a refrigerant comprising a fluorinated hydrocarbon and a polyolester-based lubricant mixed therewith, wherein the polyolester-based lubricant comprises 2-ethyl-1,3-hexanediol esterified with a mixture of mono- and dibasic carboxylic acids, the molar ratio between the monoand dibasic carboxylic acids in the mixture amounting to 50:50 to 99:1.
2. The refrigerant composition according to claim 1, wherein the diol is chemically and technically stable.
3. The refrigerant composition according to claim 1, wherein the monobasic carboxylic acid residue of the ester is derived from linear or branched C4-C18-carboxylic acids, or anhydrides or mixtures thereof.
4. The refrigerant composition according to claim 1, wherein the dibasic carboxylic acid residue is derived from oxalic acid, malonic acid, dimethyl malonic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, pimelic acid, suberic acid or azelaic acid, or a cyclic anhydride or an alkyl derivative thereof, or trimellitic anhydride.
5. The refrigerant composition according to claim 1, wherein the fluorinated hydrocarbon based refrigerant is hydrofluorocarbon 134, hydrofluorocarbon 134a, hydrofluorocarbon 143, hydrofluorocarbon 143a, hydrofluorocarbon 152 or hydrofluorocarbon 152a or a mixture of hydrofluorocarbons.
6. A refrigerant base oil comprising a complex ester of 2-ethyl-1,3-hexanediol.
7. The refrigerant composition according to claim 7, wherein the cyclic anhydride is succinic anhydride.