Hierarchical statistically multiplexed counters and a method thereof
Embodiments of the present invention relate to an architecture that uses hierarchical statistically multiplexed counters to extend counter life by orders of magnitude. Each level includes statistically multiplexed counters. The statistically multiplexed counters includes P base counters and S subcounters, wherein the S subcounters are dynamically concatenated with the P base counters. When a row overflow in a level occurs, counters in a next level above are used to extend counter life. The hierarchical statistically multiplexed counters can be used with an overflow FIFO to further extend counter life.
1. A counter architecture implemented in a network device, the counter architecture comprising a plurality of levels of statistically multiplexed counters, wherein each of the levels of statistically multiplexed counters includes N counters arranged in N/P rows, wherein each of the N/P rows includes P base counters and S subcounters, wherein any of the P base counters configured to be dynamically concatenated with one or more of the S subcounters to flexibly extend the counting capacity.
2. The counter architecture of claim 1 , wherein the N counters are wrap-around.
3. The counter architecture of claim 1 , wherein each of the P base counters initially uses one of the S subcounters.
4. The counter architecture of claim 1 , wherein the plurality of levels includes at least two levels.
5. The counter architecture of claim 1 , wherein the plurality of levels includes at least three levels.
6. The counter architecture of claim 1 , wherein each of the N/P rows also includes an overhead, wherein the overhead is an S-bit mapping of the S subcounters to the P base counters.
7. The counter architecture of claim 6 , wherein the mapping is updated upon counter expansion and upon counter shrinkage.
8. The counter architecture of claim 1 , wherein counters in the same row in a first level of the plurality of levels are shuffled into different rows in a second level of the plurality of levels.
9. The counter architecture of claim 8 , wherein a randomization of the shuffle is a bit reverse of a counter identifier of a counter, a hash function or a bit arrangement in another order.
10. The counter architecture of claim 1 , wherein the counter architecture implements a mirrored shift logic, wherein the mirror shift logic includes a lower shift logic and an upper shift logic that is the mirror of the lower shift logic.
11. The counter architecture of claim 10 , wherein a subcounter that has a rank <P/2 is associated with the lower shift logic, wherein the lower shift logic shifts the subcounter up.
12. The counter architecture of claim 10 , wherein a subcounter that has a rank ≧P/2 is associated with the upper shift logic, wherein the upper shift logic shifts the subcounter down.
13. The counter architecture of claim 1 , further comprising an overflow FIFO used and shared by the N counters in the highest level in the plurality of levels, wherein the overflow FIFO stores associated counter identifiers of all counters that are overflowing along with overflow widths.
14. The counter architecture of claim 1 , further comprising at least one interrupt sent to a CPU to read data from in the overflow FIFO and to read and clear data in a counter from each of the plurality of levels.