Aging-aware routing for NoCs
For aging-aware routing, an aging module calculates an aging score for links and routers in a Network-on-Chip for a previous epoch. A routing module dynamically routes a flow through the links and the routers to satisfy routing criteria including a least total aging score for the links and the routers of the flow.
1. A method comprising:
calculating a Traffic Threshold per Epoch (TTpE) for each link or routers of a plurality of links and routers in a Network-on-Chip (NoC) for a previous epoch before a current epoch in order to determine a fraction of nominal traffic to be accepted at each link or router of the plurality of links and routers during the current epoch, wherein calculating the TTpE for each link or router comprises:
calculating a threshold voltage change as a function of a number of interface traps per unit area and a capacitance of a metal-oxide semiconductor gate of a respective link or router;
calculating a delay variation for the respective link or router as a function of a ratio of a largest variation of performance delays of communicated signals for all critical paths of the respective link or router and a threshold voltage for the respective link or router and further as a function of the threshold voltage change for the metal-oxide semiconductor date of the respective link or router;
calculating the TTpE for the respective link or router as a function of a ratio of the delay variation for the link or router to a maximum delay variation for all links and routers in the NoC; and
routing a flow through the plurality of links and the routers to satisfy routing criteria comprising a least total calculated TTpE for the plurality of links and the routers of the flow.
2. The method of claim 1 , wherein the TTpE for each link or router of the plurality of links and routers is further calculated as a function of Negative Bias Temperature Instability (NBTI).
3. The method of claim 1 , wherein the TTpE for each link or router of the plurality of links and routers is further calculated as a function of NBTI and electromigration.
4. The method of claim 1 , wherein calculating the TTpE for each link or router of the plurality of links and routers and the routing are performed each epoch of a plurality of epochs.
5. The method of claim 1 , the method further comprising inserting an idle cycle for a link in response to a first TTpE for at least one of a link and a connected router exceeding a TTpE threshold.
6. The method of claim 1 , wherein calculating the TTpE for the respective link or router as a function of a ratio of the delay variation for the link or router to a maximum delay variation for all links and routers in the NoC comprises calculating the TTpE as TTpE=1−(Δdelay/3σdelay) where Δdelay is the delay variation for the link or router and 3σdelay is the maximum delay variation for all links and routers estimated as 3 standard deviations of a normal Gaussian distribution of the delay variations for all links and routers.
7. The method of claim 6 , further comprising calculating the TTpE for a router of the plurality of routers by transferring the TTpE for each connected link to the router.
8. The method of claim 1 , the routing criteria further comprising minimizing congestion for all flows.
9. The method of claim 1 , the routing criteria further comprising minimizing a number of links utilized for all flows.
10. The method of claim 1 , the routing criteria further comprising minimizing a performance delay for all routers of the flow and minimizing a performance delay for all links of the flow.
11. The method of claim 1 , the routing criteria further comprising minimizing energy consumption for all flows.
12. An apparatus comprising:
an aging module calculating a Traffic Threshold per Epoch (TTpE) for each link or router of a plurality of links and routers in a Network-on-Chip (NoC) for a previous epoch before a current epoch in order to determine a fraction of nominal traffic to be accepted at each link or router of the plurality of links and routers during the current epoch, wherein calculating the TTpE for each link or router comprises:
calculating a threshold voltage change as a function of a number of interface traps per unit area and a capacitance of a metal-oxide semiconductor gate of a respective link or router;
calculating a delay variation for the respective link or router as a function of a ratio of a largest variation of performance delays of communicated signals for all critical paths of the respective link or router and a threshold voltage for the link or router and further as a function of the threshold voltage change for the metal-oxide semiconductor gate of the respective link or router;
calculating the TTpE for the respective link or router as a function of a ratio of the delay variation for the respective link or router to a maximum delay variation for all links and routers in the NoC; and
a routing module routing a flow through the plurality of links and the routers to satisfy routing criteria comprising a least total calculated TTpE for the plurality of links and the routers of the flow.
13. The apparatus of claim 12 , wherein the TTpE for each link or router of the plurality of links and routers is further calculated as a function of Negative Bias Temperature Instability (NBTI).
14. The apparatus of claim 12 , wherein the TTpE for each link or router of the plurality of links and routers is further calculated as a function of NBTI and electromigration.
15. The apparatus of claim 12 , wherein calculating the TTpE for each link or router of the plurality of links and routers and the routing are performed each epoch of a plurality of epochs.
16. The apparatus of claim 12 , the routing module further inserting an idle cycle for a link in response to a first TTpE for at least one of a link and a connected router exceeding a TTpE threshold.
17. The apparatus of claim 16 , wherein calculating the TTpE for the respective link or router as a function of a ratio of the delay variation for the link or router to a maximum delay variation for all links and routers in the NoC comprises calculating the TTpE as TTpE=1−(Δdelay/3σdelay) where Δdelay is the delay variation for the link or router and 3σdelay is the maximum delay variation for all links and routers estimated as 3 standard deviations of a normal Gaussian distribution of the delay variations for all links and routers.
18. The apparatus of claim 16 , further comprising calculating the TTpE for a router of the plurality of routers by transferring the TTpE for each connected link to the router.