1. MULTI-CORE LTSMIN: MARRYING MODULARITY AND SCALABILITY ALFONS LAARMAN JOINT WORK WITH: MICHAEL WEBER JACO VAN DE POL 11/4/201 Nfm 2011

2. LTSmin Design Multi-Core Backend Concurrent Tree Compression Incremental Algorithms Experiments Future Work 23/4/2010Shared Hashtables in Parallel Model Checking 1 OVERVIEW

3. 23/4/2010 2 LTSMIN: THE MODULAR PART LTSMIN Multi-Core LTSmin: Marrying Modularity and Scalability DVE PROMELA via NIPS μCRL1 Language Frontend: … … ETF PINS Layer: Caching Regrouping Process algebraic State based muCRL2 Internal (symbolic) Symbolic Sequential Distributed Algorithms (backend) Multi-core POR

4. 23/4/2010 3 THE SCALABLE MULTI-CORE PART PREVIOUS WORK Multi-Core LTSmin: Marrying Modularity and Scalability Worker 1 Worker 2 Worker 3 Worker 4 PINS request Lockless hash table Synchronous Random Polling

5. 23/4/2010 4 MEMORY BECOMES THE PROBLEM (AGAIN) Multi-Core LTSmin: Marrying Modularity and Scalability Store 10^9 state vectors of length up to 10^3 bytes With 16 cores the throughput can become 1GB/sec of new state vectors States are very similar Solution: Tree compression without losing scalability Exploit locality with incremental algorithms

6. 23/4/2010 5 CONCURRENT TREE COMPRESSION INGREDIENTS Multi-Core LTSmin: Marrying Modularity and Scalability Alfons Laarman, Jaco van de Pol and Michael Weber – Parallel Recursive State Compression for Free (submitted)

7. 23/4/2010 6 INCREMENTAL TREE INSERTION INGREDIENTS Multi-Core LTSmin: Marrying Modularity and Scalability Incremental insertion exploits locality (log 2 (N) accesses)

8. 23/4/2010 7 MEMORY USAGE EXPERIMENTS Multi-Core LTSmin: Marrying Modularity and Scalability

9. 23/4/2010 8 MEMORY USAGE EXPERIMENTS Multi-Core LTSmin: Marrying Modularity and Scalability

10. 23/4/2010 9 AGGREGATE PERFORMANCE EXPERIMENTS Multi-Core LTSmin: Marrying Modularity and Scalability

11. 23/4/2010Shared Hashtables in Parallel Model Checking 10 SUMMARY  Scalable memory-efficient reachability (DFS/BFS)  On-the-fly model checking of safety properties

12. 23/4/2010Shared Hashtables in Parallel Model Checking 11 FUTURE WORK  POR PINS layer (benchmarked, published)  Multi-Core NDFS  Case studies Download LTSmin (open source): http://fmt.cs.utwente.nl/tools/ltsmin/

13. 23/4/2010 12 INCREMENTAL HASHING BASED ON ZOBRIST HASHING [1] AN INCREMENTAL ALGORITHM Multi-Core LTSmin: Marrying Modularity and Scalability [1] Albert Lindsey Zobrist, A New Hashing Method with Application for Game Playing ♘ g1-f3 HxHx HyHy (H x ⊕ Z ♘,g,1 ) ⊕ Z ♘,f,3 =

14. 23/4/2010Shared Hashtables in Parallel Model Checking 13 COMMAND LINE ARGUMENTS AND THEIR EFFECT LTSMIN

15. 23/4/2010 14 INCREMENTAL HASHING (CONTINUED) INGREDIENTS Multi-Core LTSmin: Marrying Modularity and Scalability Uses dependency matrix Z is now limited by L

16. 23/4/2010 15 LTSMIN: THE MODULAR PART LTSMIN Multi-Core LTSmin: Marrying Modularity and Scalability Traditionally in model checking we have states and a next-state function A state is an array of slots: ∈ S The next-state() function provides the transition relation: S → S In LTSmin, we expose static information of the specification. Partitioned Next-State Interface (PINS): S → K S (K transition groups) The Dependency Matrix D is a K × N matrix of Booleans relating slots and groups: D R i,j indicates whether slot j is read by the transitions of group i. D W i,j indicates whether slot j is written to by the transitions of group i. D i,j = D R i,j ∨ D W i,j

17. 23/4/2010 16 LTSMIN: THE MODULAR PART LTSMIN Multi-Core LTSmin: Marrying Modularity and Scalability DVE PROMELA μCRL1 ETF muCRL2 Multi-core Distributed Sequential Symbolic PINS interface