Partially Protected Caches to Reduce Failures Due to Soft Errors in Multimedia Applications Kyoungwoo Lee, Aviral Shrivastava, Ilya Issenin, Nikil Dutt, and Nalini Venkatasubramanian IEEE TRANSACTIONS ON VERY LARGE SCALE INTEGRATION (VLSI) SYSTEM Dohwan Kim

Table of contents Soft error Failure noncritical (FNC) and failure critical (FC) Partially protected cache (PPC) Design space exploration (DSE) algorithm Conclusion

Soft error A high-energy radiation particle may strike the diffusion region of a complementary metal-oxide- semiconductor transistor. This phenomenon changes the logic state of a transistor. Soft error is not repeatable error.

FNC and FC In multimedia applications Failure noncritical (FNC) data: the image data or audio data Failure critical (FC) data: the loop variable or the stack pointer

FNC and FC A cache miss, generally, is when something is looked up in the cache and is not found.

PPC Partially protected cache architecture Unprotected cache -> FNC Protected cache -> FC Increased transistor size, increased supply voltage, SEC- DED, etc

PPC It is important to choose the best configuration of a PPC to satisfy multiple design constraints such as the failure rate, power, and performance. Size of protected cache ↑ -> failure rate ↑ cache miss rate ↓ Set associativities ↑ -> performance ↑ energy consumption ↑

DSE algorithm BFExplore algorithm S: a set of sizes of the protected cache A: a set of set-associativity from 1-way to 32-way Constraints: runtime and energy consumption

DSE algorithm BFExplore algorithm

DSE algorithm BRExplore algorithm S: a set of sizes of the protected cache A: a set of set-associativity from 1-way to 32-way Constraints: failure rate and energy consumption

DSE algorithm BRExplore algorithm

Conclusion They propose PPC which can mitigate failures caused by soft errors in multimedia embedded applications. They also propose heuristic algorithms, BFExplore and BRExplore, to efficiently find the best configuration for proposed PPC architectures.