SlideShare a Scribd company logo

Can we efficiently verify concurrent programs under relaxed memory models in Maude?

Alberto Lluch Lafuente, profile picture
Alberto Lluch Lafuente

The document discusses the verification of concurrent programs under relaxed memory models using Maude, exploring various potential outcomes and challenges in memory model approximations. It highlights different strategies for verification, including program transformation and the utilization of certain tools, while also emphasizing the need for efficient search mechanisms without modifying the Maude engine. The document proposes both theoretical frameworks and practical techniques for improving verification efficiency in this context.

ScienceTechnologyEconomy & Finance
1 of 74
Downloaded 15 times
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
Can we efficiently verify concurrent programs under relaxed memory models in Maude? Yehia Abd Arrahman, Marina Andric, Alessandro Beggiato, and Alberto Lluch Lafuente WRLA 2014, 5-6 April 2014, Grenoble
I would say yes. Worth investigating Can we efficiently verify concurrent programs under relaxed memory models in Maude?
SOME MOTIVATIONS
x := 1; if y == 0 then u := 1 else skip y := 1; if x == 0 then v := 1 else skip A SIMPLE PROGRAM u v === 0 0 0 1 1 0 1 1 What are the possible outcomes for u and v?
x := 1; if y == 0 then u := 1 else skip y := 1; if x == 0 then v := 1 else skip A SIMPLE PROGRAM u v === 0 0 0 1 1 0 1 1 ✓ ??? ✓ ✓ What are the possible outcomes for u and v? ✓
MORE ANNOYANCES... x := 1 Maude> search P =>* Q . ... States: 10!? x := 2P =
while true do x := 0 Maude> search P =>* Q . Zzz... P = MORE ANNOYANCES...
THE FREE LUNCH IS OVER Herb Sutter. “The free lunch is over”, Dr. Dobb's Journal, 30(3), March 2005 and C/C++ Users Journal, 23(2), February 2005. < “some optimizations are actually far more than optimizations, in that they can change the meaning of programs and cause visible effects that can break reasonable programmer expectations. CPU designers are generally sane and well-adjusted folks but they are under so much pressure that they'll risk changing the meaning of your program, and possibly break it, in order to make it run faster. “
Dekker Peterson Lamport Szymanski 0 100 200 300 400 500 600 700 800 900 1000 Sequentially Consistent Relaxed (incorrect) Relaxed (corrected) STATE SPACE SIZE: SC vs RMM
Dekker Peterson Lamport Szymanski 0 200 400 600 800 1000 1200 No reduction Some approximation Some other approximation Partial-Order-Reduction Some combination REDUCTIONS (verification)
Dekker Peterson Lamport Szymanski 0 50 100 150 200 250 300 350 400 450 Breadth-First Search Best-First with some heuristic Best-First with some other heuristic Best-First with yet another heuristic REDUCTIONS (bug-finding)
RELAXED MEMORY MODELS
SEQUENTIAL CONSISTENCY “A multiprocessor system is sequentially consistent if the result of any execution is the same as if the operations of all the processors were executed in some sequential order, and the operations of each individual processor appear in this sequence in the order specified by its program.” - Leslie Lamport, "How to Make a Multiprocessor Computer That Correctly Executes Multiprocess Programs", IEEE Trans. Comput, 1979 Program order: among operations from individual processors Atomicity: memory operations must execute atomically with respect to each other
RELAXING CONSISTENCY Relaxing program order:  Write-to-Read  Write-to-Write  Read-to-Read  Read-to-Write Relaxing atomicity:  Read own write early  Read others’ write early
HIERARCHY OF RELAXATIONS SC TSO IBM-370 PC RCsc PowerPC WO Alpha RCPc RMO PSO Write-to-Read Write-to-Write Read-to-Read Read-to-Write source: http://wiki.expertiza.ncsu.edu/index.php/CSC/ECE_506_Spring_2013/10c_ks
TOTAL STORE ORDERING (TSO) Relaxations:  Write-to-Read  Read own write early Why?  Mitigate write latency  Some programs may still be “correct” (e.g. sequentially consistent)
TSO “AXIOMATICALLY” TSO-executions are sequences of reads and writes r(x,u) < r(y,v) < w(z,w) < ...
TSO “AXIOMATICALLY” TSO-executions are sequences of reads and writes r(x,u) < r(y,v) < w(z,w) < ... such that r <p r' => r < r' [r-r preserved] r <p w' => r < w' [r-w preserved] w <p w' => w < w' [w-w preserved] w-r allowed
TSO “AXIOMATICALLY” TSO-executions are sequences of reads and writes r(x,u) < r(y,v) < w(z,w) < ... such that r <p r' => r < r' [r-r preserved] r <p w' => r < w' [r-w preserved] w <p w' => w < w' [w-w preserved] and r(x,u) are such that (1) v if s(x,v) is the max wrt. < among all s(x,v) s.t. s(x,v) < r(x,u) or s(x,v) <p r(x,u) (2) x0 (initial value for x) if there is no s(x,v) above. (read own's write early) w-r allowed
TSO “OPERATIONALLY” SHARED MEMORY THREAD THREAD
TSO “OPERATIONALLY” SHARED MEMORY THREAD THREAD WRITE BUFFER WRITE BUFFER
Formalization of memory models  Axiomatic [Adve, Alglage, Sewel, Owens, Higham,...]  Operational [Boudol, Petri, Atig, Bouajjani, Burckhardt,...]  Adequacy, generality, etc. Correctness criteria  Sequential consistency, linearizability, serializability, quiescent/eventual consistency... [Herlihy, Shavit, Shapiro,...]  “Fundamental property” (data-race free programs are sequential consistent) [Saraswat et al.] Portability of programs  Check whether P/SC ≈ P/RMM  Otherwise repair P e.g. inserting fences [Wolper, Bouajjani...] SOME KEY ISSUES
Verification approaches  Directly use SC verification tools e.g. for programs that are linearizable even under RMMs [Burckhardt, Cohen, Owens]  Program Transformation and then SC tools e.g. [Alglave, Bouajjani]  Ad-hoc verification under RMMs. e.g. Some... (see later) Some tools  CBMC [Alglave et al]  CheckFence [Burckhardt et al]  DFENCE [Lui et al] SOME KEY ISSUES
THIS TALK's PERSPECTIVE
OUR SPIRIT HERE  Language designers prototyping new RMM- aware languages with Maude (the natural framework!).  Interested in “search” for P/RMM (for checking properties, for fence insertions, etc.).  Willing to make search efficient but not willing to modify the Maude engine.
A SIMPLE MULTI-THREADED LANGUAGE
A SIMPLE LANGUAGE
CONFIGURATIONS
MEMORIES AND VIEWS Memory updates Local to Global In the following abbreviates
SEMANTICS: thread interleaving sorry...
SEMANTICS: skip
SEMANTICS: assignments
SEMANTICS: fences
SEMANTICS: sequential composition
SEMANTICS: branches
SEMANTICS: loops
SEMANTICS: wait
SEMANTICS: buffer commits
MORE ANNOYANCES... x := 1 Maude> search P =>* Q . ... States: 10!? x := 2P =
x|->0 =============== || --------------- x:=1; || x:=2; x|->0 =============== x|->1 || --------------- skip || x:=2; x|->0 =============== || x|->2 --------------- x:=1 || skip x|->0 =============== x|->1 || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || x:=2; x|->2 =============== || --------------- x:=1 || skip x|->1 =============== || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || skip x|->2 =============== x|->1 || --------------- skip || skip x:=1; x:=1; x:=1; x:=2; x:=2; x:=2; commit commit commit commit commitcommit x|->2 =============== || --------------- skip || skip state Shared memory Thread buffer Thread program
x|->0 =============== || --------------- x:=1; || x:=2; x|->0 =============== x|->1 || --------------- skip || x:=2; x|->0 =============== || x|->2 --------------- x:=1 || skip x|->0 =============== x|->1 || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || x:=2; x|->2 =============== || --------------- x:=1 || skip x|->1 =============== || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || skip x|->2 =============== x|->1 || --------------- skip || skip x:=1; x:=1; x:=1; x:=2; x:=2; x:=2; commit commit commit commit commitcommit x|->2 =============== || --------------- skip || skip state Shared memory Thread buffer Thread program Usual state space with SC
while true do x := 0 Maude> search P =>* Q . Zzz... P = MORE ANNOYANCES...
x|->0 ==================== -------------------- while(true) do x:=0 x|->0 ==================== -------------------- x:=0; while(true) do x:=0 while(true) x:=0; x|->0 ==================== x|->0 -------------------- while(true) do x:=0 x|->0 ==================== x|->0 -------------------- x:=0; while(true) do x:=0 while(true) x|->0 ==================== x|->0 x|->0 -------------------- while(true) do x:=0 while(true) x:=0; commit commit commit ...
SOME REDUCTION TECHNIQUES
Partial Order Reduction Techniques  Partial Orders [Alglave et al. @ CAV 2013]  Persistent Sets [Linden&Wolper @ TACAS 2013]  Ample sets (via SPIN) [Jonson @ CAN2009] Approximation/abstraction techniques  Predicate abstraction [Dan et al. @ SAS 2013]  Bounded context-switches [Abdulla et al. @ TACAS 2012]  Single-buffer semantics [Atig et al. @ CAV 2011]  Buffers-as-sets abstraction [Kuperstein et al. @ PLDI 2011]  Bounded buffers [Kuperstein et al. @ FMCAD 2011] Other  SAT/BMC [Burckhardt et al @ CAV 6/7/8, Gopalakrishnan et al. @ CAV 04]  Buffer automata [Linden&Wolper @ SPIN2010, TACAS 2013]  Monitors [Burnim et al. @ TACAS 2011, Burckhardt&Musuvathi @ CAV 2008] TEN+ YEARS OF RESEARCH Equational abstractions? [Meseguer&Palomino&Martí-Oliet @ TCS 2008] Partial-order reduction? [Farzan&Meseguer @ TERMGRAPH 2006] Search strategies? [Martí-Oliet&Meseguer&Verdejo @ WRLA 2004]
SOME SIMPLE APPROXIMATIONS FOR TSO Disclaimer: proof-of-concepts, for the “good” ones see the above cited papers.
ONE OF OUR ANOYANCES while true do x := 0 Maude> search P =>* Q . Zzz..
BUFFERS AS SETS OF UPDATES Abstract buffers as sets of updates:  Make ACI1 (i.e. buffer becomes sets of updates);  Make commit non-deterministic (usual+no effect);  Make evaluation of expressions non-deterministic. You get an over-approximation:  Finite state space;  Preservation of reachability properties.  (Possibly) some “spurious” behaviours;
Dekker Peterson Lamport Szymanski 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 No reduction Buffers-as-Sets Buffers-as-Ordered-Maps Force-Flush MORE STATES
BUFFERS AS ORDERED MAPS Approximation that  Guarantees finite state space;  Introduces some executions;  Preserves some reachability properties??? (under investigation)
“SPURIOUS” EXECUTIONS x:=1; y:=1; x:=2 wait x=0 & y=1
x|->0 , y |->0 =============== || --------------- x:=1; || wait(...) y:=1; || x:=2 || x|->0 , y |->0 =============== x|->1 || --------------- y:=1; || wait(...) x:=2; || x|->0 , y |->0 =============== x|->1 || y|->1 || --------------- x:=2; || wait(...) x|->0 , y |->0 =============== x|->1 || y|->1 || x|->2 || --------------- skip || wait(...) x|->1 , y |->0 =============== || --------------- y:=1; || wait(...) x:=2; || x|->1 , y |->0 =============== y|->1 || --------------- x:=2; || wait(...) x|->1 , y |->0 =============== y|->1 || x|->2 || --------------- skip || wait(...) x|->1 , y |->1 =============== || --------------- x:=2; || wait(...) x|->1 , y |->1 =============== x|->2 || --------------- skip || wait(...) x|->2 , y |->1 =============== || --------------- skip || wait(...) commit commitcommit commit commit commit x|->0 , y |->0 =============== y|->1 || x|->2 || --------------- skip || wait(...) wait! ONE “SPURIOUS” EXECUTION x|->0 , y |->1 =============== y|->1 || --------------- skip || wait(...) commit
Dekker Peterson Lamport Szymanski 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 No reduction Buffers-as-Sets Buffers-as-Ordered-Maps Force-Flush REDUCTIONS
FORCE-FLUSH APPROXIMATION Under-approximation that  Does not guarantee finite state space ;  Some behaviours may be lost;  Does not introduce spurious behaviours. (up to some equivalence: stuttering and depending on the state observations).
M =============== x|->u || ... || x|->v || --------------- S || T M ◦ x|->u =============== ... || x|->v || --------------- S || T NO “SPURIOUS” EXECUTION M =============== x|->u || ... || || --------------- x:=v; S || T M ◦ x|->u =============== ... || || --------------- x:=v; S || T commit x:=v x:=v (up to some equivalence: stuttering and depending on the state observations).
Dekker Peterson Lamport Szymanski 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 No reduction Buffers-as-Sets Buffers-as-Ordered-Maps Force-Flush REDUCTIONS
PARTIAL-ORDER REDUCTION FOR RMMs
AMPLE SETS Main idea  Explore only a subset ample(s) of the succesors of s...  ...such that ample(s): C0: ample(s) empty only if s is a deadlock; C1: ample(s) contains invisible actions; C2: no transition that is dependent on a transition in ample(s) occurs in the original system without a transition in ample(s) occurring first; C3: no action outside ample(s) is delayed forever.  You will get a stutter equivalent transition system.
SIMPLE POR FOR TSO Simple heuristic: assignments x := u are independent of actions of other threads since their effect is local (on the buffer). They are also invisible unless one wants to observe buffers or programs.
Dekker Peterson Lamport Szymanski 0 100 200 300 400 500 600 700 800 900 1000 No reduction Partial-Order Reduction REDUCTIONS (verification)
SEARCH STRATEGIES FOR RMMs
DIRECTED MODEL CHECKING Main idea  Replace the exploration algorithm (NDFS/BFS) by a “guided” algorithm (A*, Best-First, etc.)  Domain/property-based “heuristic” functions to rank states or executions “Heuristics for model checking Java” [Groce&Visser]  Promote interleavings (we think “sequentially”)  Promote code coverage Done for JPF, SPIN, etc.
x|->0 , y|->0 =============== || --------------- x:=1; || y:=1; y==0? || x==0? x|->0 , y|->0 =============== x->1 || --------------- y==0? || y:=1; || x==0? x|->0 , y|->0 =============== || y->1 --------------- x:=1 || x==0? y==0? || x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || x==0? x|->1 , y|->0 =============== || --------------- y==0? || y:=1; || x==0? x|->0 , y|->1 =============== || --------------- X:=1 || x==0? y==0? || x:=1; x:=1; y:=1; y:=1;flush flush ... ... x|->0 , y|->0 =============== x->1 || y->1 --------------- cs || x==0? x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || cs
x|->0 , y|->0 =============== || --------------- x:=1; || y:=1; y==0? || x==0? x|->0 , y|->0 =============== x->1 || --------------- y==0? || y:=1; || x==0? x|->0 , y|->0 =============== || y->1 --------------- x:=1 || x==0? y==0? || x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || x==0? x|->1 , y|->0 =============== || --------------- y==0? || y:=1; || x==0? x|->0 , y|->1 =============== || --------------- X:=1 || x==0? y==0? || x:=1; x:=1; y:=1; y:=1;flush flush 0 0 0 2 1 0 0 0 1 ... ... x|->0 , y|->0 =============== x->1 || y->1 --------------- cs || x==0? x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || cs 2 2 Count number of non-empty buffers
Dekker Peterson Lamport Szymanski 0 50 100 150 200 250 300 350 400 450 Breadth-First Search Best-First + "number of non-empty buffers" heuristic Best-First + "number of pending writes" heuristic Best-First + "number of inconsistent pending writes" heuristic REDUCTIONS (bug-finding)
CONCLUDING REMARKS
I would say yes. Worth investigating Can we efficiently verify concurrent programs under relaxed memory models in Maude?
Beyond TSO: PSO, RMO, etc.1 2 FUTURE WORK? Other languages/primitives: see e.g. KernelC/x86-TSO in K [Serbanuta] 3 Proof techniques (with Maude)
TAHNSK!
REFERENCES
[Linden&Wolper @ TACAS 2013] Alexander Linden, Pierre Wolper: A Verification-Based Approach to Memory Fence Insertion in PSO Memory Systems. TACAS 2013: 339-353 [Dan&MMeshman&Vechev&Yahav @ SAS 2013] Andrei Marian Dan, Yuri Meshman, Martin T. Vechev, Eran Yahav: Predicate Abstraction for Relaxed Memory Models. SAS 2013: 84-104 [Alglave et al. @ CAV 2013] Jade Alglave, Daniel Kroening, Michael Tautschnig: Partial Orders for Efficient Bounded Model Checking of Concurrent Software. CAV 2013: 141-157 [Abdulla&Atig&Chen&Leonardsson&Rezine @ TACAS 2012] Abdulla, P.A., Atig, M.F., Chen, Y.-F., Leonardsson, C., Rezine, A.: Counter- Example Guided Fence Insertion under TSO. In: TACAS 2012. LNCS, vol. 7214 (2012) [Atig&Bouajjani&Parlato @ CAV 2011] Atig, M.F., Bouajjani, A., Parlato, G.: Getting Rid of Store-Buffers in TSO Analysis. In: Gopalakrishnan, G., Qadeer, S. (eds.) CAV 2011. LNCS, vol. 6806 (2011) [Kuperstein&Vechev&Yahav @ PLDI 2011] Kuperstein, M., Vechev, M., Yahav, E.: Partial-coherence abstractions for relaxed memory models. In: PLDI 2011 (2011) REFERENCES (1)
[Burnim&Sen&Stergiou @ TACAS 2011] Jacob Burnim, Koushik Sen, Christos Stergiou: Sound and Complete Monitoring of Sequential Consistency for Relaxed Memory Models. TACAS 2011: 11-25 [Burnim&Sen& C. Stergiou @ TACAS 2011] J. Burnim, K. Sen, and C. Stergiou. Sound and complete monitoring of sequential consistency in relaxed memory models. In TACAS, 2011. [Kuperstein&Vechev&Yahav @ FMCAD 2011] M. Kuperstein, M. Vechev, and E. Yahav. Automatic inference of memory fences. In FMCAD, 2011. [Linedn&Wolper @ SPIN 2010] A. Linden and P. Wolper. An automata-based symbolic approach for verifying programs on relaxed memory models. In SPIN, 2010. [Jonson @ CAN2009] Jonsson, B.: State-space exploration for concurrent algorithms under weak memory orderings: (preliminary version). SIGARCH Comput. Archit. News 36, 65–71 (2009) [Burckhardt&Musuvathi @ CAV 2008] Burckhardt,S.,Musuvathi,M.: Effective Program Verification for Relaxed Memory Models. In: Gupta, A., Malik, S. (eds.) CAV 2008. LNCS, vol. 5123, pp. 107–120. Springer, Heidelberg (2008) REFERENCES (2)
[Burckhardt&Alur&Martin @ CAV 2007] Burckhardt, S., Alur, R., Martin, M.M.K.: Checkfence: checking consistency of concurrent data types on relaxed memory models. In: ACM SIGPLAN 2007 Conference on Programming Lan- guage Design and Implementation (2007) [Burckhardt&Alur&Martin @ CAV 2006] Burckhardt,S.,Alur,R.,Martin,M.M.K.: Bounded Model Checking of Concurrent Data Types on Relaxed Memory Models: A Case Study. In: CAV 2006. LNCS 4144. (2006) [Gopalakrishnan&Yang&Sivaraj @ CAV 2004] Gopalakrishnan, G., Yang, Y., Sivaraj, H.: QB or not QB: An efficient execution verification tool for memory orderings. In: CAV 2004. LNCS, vol. 3114 (2004) [Park&Dill @ PAA 1995] Park, S., Dill, D.L.: An executable specification, analyzer and verifier for rmo (relaxed memory order). In: SPAA 1995: Proceedings of the Seventh Annual ACM Symposium on Parallel Algorithms and Architectures, pp. 34–41. ACM, New York (1995) REFERENCES (3)
[Meseguer&Palomino&Martí-Oliet @ TCS 2008] José Meseguer, Miguel Palomino, Narciso Martí-Oliet: Equational abstractions. Theor. Comput. Sci. 403(2-3): 239-264 (2008) [Farzan&Meseguer @ TERMGRAPH 2006] Azadeh Farzan, José Meseguer: Partial Order Reduction for Rewriting Semantics of Programming Languages. Electr. Notes Theor. Comput. Sci. 176(4): 61-78 (2007) [Rodríguez 2009 @ WRLA 2009] Rodríguez, D.E.: Combining techniques to reduce state space and prove strong properties. In: WRLA. Volume 238(3) of ENTCS. (2009) 267 – 280 [Lluch&Meseguer&Vandin @ ICFEM 2012] Alberto Lluch-Lafuente, José Meseguer, Andrea Vandin: State Space c-Reductions of Concurrent Systems in Rewriting Logic. ICFEM 2012: 430-446 [Martí-Oliet&Meseguer&Verdejo @ WRLA 2004] Narciso Martí-Oliet, José Meseguer, Alberto Verdejo: Towards a Strategy Language for Maude. Electr. Notes Theor. Comput. Sci. 117: 417-441 (2005) [Groce&Visser @ STTT 2004] Alex Groce, Willem Visser: Heuristics for model checking Java programs. STTT 6(4): 260-276 (2004) REFERENCES (4)

More Related Content

PPT
Schemaless Databases
Dan Gunter
 
PPT
Metamorphosis from Forms to Java: a technical lead's perspective
Michael Fons
 
PPTX
Software Characterization & Performance Testing - Beat Your Software with a S...
Tze Chin Tang
 
PDF
OpenControl Overview - Joshua McKenty
Julie Coonce
 
PDF
Adrian Colyer - Keynote: NoSQL matters - NoSQL matters Dublin 2015
NoSQLmatters
 
PDF
oops.pdf
AnirudhReddy659342
 
PPTX
Neotys PAC - Stijn Schepers
Neotys_Partner
 
PPTX
What is java?-Saurabh Upadhyay
Saurabh Upadhyay
 
Schemaless Databases
Dan Gunter
 
Metamorphosis from Forms to Java: a technical lead's perspective
Michael Fons
 
Software Characterization & Performance Testing - Beat Your Software with a S...
Tze Chin Tang
 
OpenControl Overview - Joshua McKenty
Julie Coonce
 
Adrian Colyer - Keynote: NoSQL matters - NoSQL matters Dublin 2015
NoSQLmatters
 
oops.pdf
AnirudhReddy659342
 
Neotys PAC - Stijn Schepers
Neotys_Partner
 
What is java?-Saurabh Upadhyay
Saurabh Upadhyay
 

Similar to Can we efficiently verify concurrent programs under relaxed memory models in Maude? (20)

PDF
Sulthan's_JAVA_Material_for_B.Sc-CS.pdf
SULTHAN BASHA
 
PPTX
DevOps@Morpho in 2014
Jean-Charles JOREL
 
PDF
DevOps for absolute beginners
Ahmed Misbah
 
PDF
Product! - The road to production deployment
Filippo Zanella
 
PDF
Pmp memory-sheets
chandrashekhar khambekar
 
DOCX
Report hospital
Rachit Gaur
 
PDF
Python Programming - III. Controlling the Flow
Ranel Padon
 
PDF
OOP Java
Saif Kassim
 
PDF
WoMakersCode 2016 - Shit Happens
Jackson F. de A. Mafra
 
PPTX
PARADIGM IT.pptx
jamesmarken1
 
PDF
Scaling and Embracing Failure: Clustering Docker with Mesos
Rob Gulewich
 
PPTX
Sql server baselines
Mike Walsh
 
PPTX
Cse
Yashitha11
 
PDF
RTOS - Real Time Operating Systems
Emertxe Information Technologies Pvt Ltd
 
PPTX
FRC Reporting Beginner Course
Khalil Rehman NLP (MPrac) MCIPS, PMP,OCP
 
PPTX
Oracle Fusion Financial Report Centre Reporting Beginner course
Khalil Rehman NLP (MPrac) MCIPS, PMP,OCP
 
PDF
DevOps feedback loops
Paul Peissner
 
PPTX
Lesson 1 of c programming algorithms and flowcharts.pptx
AlinaMishra7
 
PPTX
Aug NYC July 12 event
AUGNYC
 
PDF
Frequently asked MuleSoft Interview Questions and Answers from Techlightning
Arul ChristhuRaj Alphonse
 
Sulthan's_JAVA_Material_for_B.Sc-CS.pdf
SULTHAN BASHA
 
DevOps@Morpho in 2014
Jean-Charles JOREL
 
DevOps for absolute beginners
Ahmed Misbah
 
Product! - The road to production deployment
Filippo Zanella
 
Pmp memory-sheets
chandrashekhar khambekar
 
Report hospital
Rachit Gaur
 
Python Programming - III. Controlling the Flow
Ranel Padon
 
OOP Java
Saif Kassim
 
WoMakersCode 2016 - Shit Happens
Jackson F. de A. Mafra
 
PARADIGM IT.pptx
jamesmarken1
 
Scaling and Embracing Failure: Clustering Docker with Mesos
Rob Gulewich
 
Sql server baselines
Mike Walsh
 
Cse
Yashitha11
 
RTOS - Real Time Operating Systems
Emertxe Information Technologies Pvt Ltd
 
FRC Reporting Beginner Course
Khalil Rehman NLP (MPrac) MCIPS, PMP,OCP
 
Oracle Fusion Financial Report Centre Reporting Beginner course
Khalil Rehman NLP (MPrac) MCIPS, PMP,OCP
 
DevOps feedback loops
Paul Peissner
 
Lesson 1 of c programming algorithms and flowcharts.pptx
AlinaMishra7
 
Aug NYC July 12 event
AUGNYC
 
Frequently asked MuleSoft Interview Questions and Answers from Techlightning
Arul ChristhuRaj Alphonse
 
Ad

More from Alberto Lluch Lafuente (16)

PDF
Many-to-Many Information Flow Policies
Alberto Lluch Lafuente
 
PDF
Aggregate Programming through a Soft Modal Logic
Alberto Lluch Lafuente
 
PDF
A Semiring-valued Temporal Logic
Alberto Lluch Lafuente
 
PDF
Collaborative Task Execution In Volunteer Clouds (or how to choose a sub-revi...
Alberto Lluch Lafuente
 
PDF
State Space C-Reductions @ ETAPS Workshop GRAPHITE 2013
Alberto Lluch Lafuente
 
PDF
Adaptable Transition Systems @ ASCENS Meeting Prague 2013
Alberto Lluch Lafuente
 
PDF
White Box Adaptation @ CINA Meeting 2013
Alberto Lluch Lafuente
 
PDF
A White-box Perspective on Self-Adaptation and Self-Awareness (with a focus o...
Alberto Lluch Lafuente
 
PDF
State Space c-Reductions of Concurrent Systems in Rewriting Logic @ ETAPS Wor...
Alberto Lluch Lafuente
 
ODP
A conceptual framework for behavioural adaptation @ Leicester 2011
Alberto Lluch Lafuente
 
PDF
Evaluating the performance of model transformation styles with Maude @ Sympos...
Alberto Lluch Lafuente
 
PDF
A conceptual framework for behavioural adaptation @ Meeting ASCENS 2011
Alberto Lluch Lafuente
 
PDF
Maude .:° ASCENS 2011
Alberto Lluch Lafuente
 
PDF
IMT Welcome Day 2011
Alberto Lluch Lafuente
 
PDF
A Graph Syntax for Processes and Services @ Workshop WS-FM 2009
Alberto Lluch Lafuente
 
PDF
An Algebra of Hierarchical Graphs
Alberto Lluch Lafuente
 
Many-to-Many Information Flow Policies
Alberto Lluch Lafuente
 
Aggregate Programming through a Soft Modal Logic
Alberto Lluch Lafuente
 
A Semiring-valued Temporal Logic
Alberto Lluch Lafuente
 
Collaborative Task Execution In Volunteer Clouds (or how to choose a sub-revi...
Alberto Lluch Lafuente
 
State Space C-Reductions @ ETAPS Workshop GRAPHITE 2013
Alberto Lluch Lafuente
 
Adaptable Transition Systems @ ASCENS Meeting Prague 2013
Alberto Lluch Lafuente
 
White Box Adaptation @ CINA Meeting 2013
Alberto Lluch Lafuente
 
A White-box Perspective on Self-Adaptation and Self-Awareness (with a focus o...
Alberto Lluch Lafuente
 
State Space c-Reductions of Concurrent Systems in Rewriting Logic @ ETAPS Wor...
Alberto Lluch Lafuente
 
A conceptual framework for behavioural adaptation @ Leicester 2011
Alberto Lluch Lafuente
 
Evaluating the performance of model transformation styles with Maude @ Sympos...
Alberto Lluch Lafuente
 
A conceptual framework for behavioural adaptation @ Meeting ASCENS 2011
Alberto Lluch Lafuente
 
Maude .:° ASCENS 2011
Alberto Lluch Lafuente
 
IMT Welcome Day 2011
Alberto Lluch Lafuente
 
A Graph Syntax for Processes and Services @ Workshop WS-FM 2009
Alberto Lluch Lafuente
 
An Algebra of Hierarchical Graphs
Alberto Lluch Lafuente
 
Ad

Recently uploaded (20)

PPTX
microscope-Lecturecjchchchchcuvuvhc.pptx
jaylaurencenobleza
 
PPTX
TOTAL hIP ARTHROPLASTY Presentation.pptx
hararghemssc
 
PPTX
Introduction to Cardiovascular system_structure and functions-1
muralinath2
 
PDF
VARICELLA VACCINATION: A POTENTIAL STRATEGY FOR PREVENTING MULTIPLE SCLEROSIS
ijab2
 
PPTX
ECG_Course_Presentation د.محمد صقران ppt
lelouchml1995
 
PPTX
Classification Systems_TAXONOMY_SCIENCE8.pptx
glofernignacio
 
PPTX
Introduction to Fisheries Biotechnology_Lesson 1.pptx
Esther Pongcol
 
PPTX
2Systematics of Living Organisms t-.pptx
RachanaT6
 
PPTX
INTRODUCTION TO EVS | Concept of sustainability
manumaddy15198
 
PPTX
EPIDURAL ANESTHESIA ANATOMY AND PHYSIOLOGY.pptx
PrabakaranMP1
 
PPTX
ognitive-behavioral therapy, mindfulness-based approaches, coping skills trai...
OliveJolly1
 
PPTX
GEN. BIO 1 - CELL TYPES & CELL MODIFICATIONS
breeysal7
 
PDF
Placing the Near-Earth Object Impact Probability in Context
Sérgio Sacani
 
PDF
Mastering Bioreactors and Media Sterilization: A Complete Guide to Sterile Fe...
Sabina Sharma
 
PPT
The World of Physical Science, • Labs: Safety Simulation, Measurement Practice
joybejerano
 
PDF
HPLC-PPT.docx high performance liquid chromatography
darshanambiga1633
 
PDF
CAPERS-LRD-z9:AGas-enshroudedLittleRedDotHostingaBroad-lineActive GalacticNuc...
Sérgio Sacani
 
PDF
IFIT3 RNA-binding activity primores influenza A viruz infection and translati...
saracelre
 
PDF
The scientific heritage No 166 (166) (2025)
The scientific heritage
 
PDF
Sciences of Europe No 170 (2025)
Sciences of Europe
 
microscope-Lecturecjchchchchcuvuvhc.pptx
jaylaurencenobleza
 
TOTAL hIP ARTHROPLASTY Presentation.pptx
hararghemssc
 
Introduction to Cardiovascular system_structure and functions-1
muralinath2
 
VARICELLA VACCINATION: A POTENTIAL STRATEGY FOR PREVENTING MULTIPLE SCLEROSIS
ijab2
 
ECG_Course_Presentation د.محمد صقران ppt
lelouchml1995
 
Classification Systems_TAXONOMY_SCIENCE8.pptx
glofernignacio
 
Introduction to Fisheries Biotechnology_Lesson 1.pptx
Esther Pongcol
 
2Systematics of Living Organisms t-.pptx
RachanaT6
 
INTRODUCTION TO EVS | Concept of sustainability
manumaddy15198
 
EPIDURAL ANESTHESIA ANATOMY AND PHYSIOLOGY.pptx
PrabakaranMP1
 
ognitive-behavioral therapy, mindfulness-based approaches, coping skills trai...
OliveJolly1
 
GEN. BIO 1 - CELL TYPES & CELL MODIFICATIONS
breeysal7
 
Placing the Near-Earth Object Impact Probability in Context
Sérgio Sacani
 
Mastering Bioreactors and Media Sterilization: A Complete Guide to Sterile Fe...
Sabina Sharma
 
The World of Physical Science, • Labs: Safety Simulation, Measurement Practice
joybejerano
 
HPLC-PPT.docx high performance liquid chromatography
darshanambiga1633
 
CAPERS-LRD-z9:AGas-enshroudedLittleRedDotHostingaBroad-lineActive GalacticNuc...
Sérgio Sacani
 
IFIT3 RNA-binding activity primores influenza A viruz infection and translati...
saracelre
 
The scientific heritage No 166 (166) (2025)
The scientific heritage
 
Sciences of Europe No 170 (2025)
Sciences of Europe
 

Can we efficiently verify concurrent programs under relaxed memory models in Maude?

  • 1. Can we efficiently verify concurrent programs under relaxed memory models in Maude? Yehia Abd Arrahman, Marina Andric, Alessandro Beggiato, and Alberto Lluch Lafuente WRLA 2014, 5-6 April 2014, Grenoble
  • 2. I would say yes. Worth investigating Can we efficiently verify concurrent programs under relaxed memory models in Maude?
  • 4. x := 1; if y == 0 then u := 1 else skip y := 1; if x == 0 then v := 1 else skip A SIMPLE PROGRAM u v === 0 0 0 1 1 0 1 1 What are the possible outcomes for u and v?
  • 5. x := 1; if y == 0 then u := 1 else skip y := 1; if x == 0 then v := 1 else skip A SIMPLE PROGRAM u v === 0 0 0 1 1 0 1 1 ✓ ??? ✓ ✓ What are the possible outcomes for u and v? ✓
  • 6. MORE ANNOYANCES... x := 1 Maude> search P =>* Q . ... States: 10!? x := 2P =
  • 7. while true do x := 0 Maude> search P =>* Q . Zzz... P = MORE ANNOYANCES...
  • 8. THE FREE LUNCH IS OVER Herb Sutter. “The free lunch is over”, Dr. Dobb's Journal, 30(3), March 2005 and C/C++ Users Journal, 23(2), February 2005. < “some optimizations are actually far more than optimizations, in that they can change the meaning of programs and cause visible effects that can break reasonable programmer expectations. CPU designers are generally sane and well-adjusted folks but they are under so much pressure that they'll risk changing the meaning of your program, and possibly break it, in order to make it run faster. “
  • 9. Dekker Peterson Lamport Szymanski 0 100 200 300 400 500 600 700 800 900 1000 Sequentially Consistent Relaxed (incorrect) Relaxed (corrected) STATE SPACE SIZE: SC vs RMM
  • 10. Dekker Peterson Lamport Szymanski 0 200 400 600 800 1000 1200 No reduction Some approximation Some other approximation Partial-Order-Reduction Some combination REDUCTIONS (verification)
  • 11. Dekker Peterson Lamport Szymanski 0 50 100 150 200 250 300 350 400 450 Breadth-First Search Best-First with some heuristic Best-First with some other heuristic Best-First with yet another heuristic REDUCTIONS (bug-finding)
  • 13. SEQUENTIAL CONSISTENCY “A multiprocessor system is sequentially consistent if the result of any execution is the same as if the operations of all the processors were executed in some sequential order, and the operations of each individual processor appear in this sequence in the order specified by its program.” - Leslie Lamport, "How to Make a Multiprocessor Computer That Correctly Executes Multiprocess Programs", IEEE Trans. Comput, 1979 Program order: among operations from individual processors Atomicity: memory operations must execute atomically with respect to each other
  • 14. RELAXING CONSISTENCY Relaxing program order:  Write-to-Read  Write-to-Write  Read-to-Read  Read-to-Write Relaxing atomicity:  Read own write early  Read others’ write early
  • 15. HIERARCHY OF RELAXATIONS SC TSO IBM-370 PC RCsc PowerPC WO Alpha RCPc RMO PSO Write-to-Read Write-to-Write Read-to-Read Read-to-Write source: http://wiki.expertiza.ncsu.edu/index.php/CSC/ECE_506_Spring_2013/10c_ks
  • 16. TOTAL STORE ORDERING (TSO) Relaxations:  Write-to-Read  Read own write early Why?  Mitigate write latency  Some programs may still be “correct” (e.g. sequentially consistent)
  • 17. TSO “AXIOMATICALLY” TSO-executions are sequences of reads and writes r(x,u) < r(y,v) < w(z,w) < ...
  • 18. TSO “AXIOMATICALLY” TSO-executions are sequences of reads and writes r(x,u) < r(y,v) < w(z,w) < ... such that r <p r' => r < r' [r-r preserved] r <p w' => r < w' [r-w preserved] w <p w' => w < w' [w-w preserved] w-r allowed
  • 19. TSO “AXIOMATICALLY” TSO-executions are sequences of reads and writes r(x,u) < r(y,v) < w(z,w) < ... such that r <p r' => r < r' [r-r preserved] r <p w' => r < w' [r-w preserved] w <p w' => w < w' [w-w preserved] and r(x,u) are such that (1) v if s(x,v) is the max wrt. < among all s(x,v) s.t. s(x,v) < r(x,u) or s(x,v) <p r(x,u) (2) x0 (initial value for x) if there is no s(x,v) above. (read own's write early) w-r allowed
  • 21. TSO “OPERATIONALLY” SHARED MEMORY THREAD THREAD WRITE BUFFER WRITE BUFFER
  • 22. Formalization of memory models  Axiomatic [Adve, Alglage, Sewel, Owens, Higham,...]  Operational [Boudol, Petri, Atig, Bouajjani, Burckhardt,...]  Adequacy, generality, etc. Correctness criteria  Sequential consistency, linearizability, serializability, quiescent/eventual consistency... [Herlihy, Shavit, Shapiro,...]  “Fundamental property” (data-race free programs are sequential consistent) [Saraswat et al.] Portability of programs  Check whether P/SC ≈ P/RMM  Otherwise repair P e.g. inserting fences [Wolper, Bouajjani...] SOME KEY ISSUES
  • 23. Verification approaches  Directly use SC verification tools e.g. for programs that are linearizable even under RMMs [Burckhardt, Cohen, Owens]  Program Transformation and then SC tools e.g. [Alglave, Bouajjani]  Ad-hoc verification under RMMs. e.g. Some... (see later) Some tools  CBMC [Alglave et al]  CheckFence [Burckhardt et al]  DFENCE [Lui et al] SOME KEY ISSUES
  • 25. OUR SPIRIT HERE  Language designers prototyping new RMM- aware languages with Maude (the natural framework!).  Interested in “search” for P/RMM (for checking properties, for fence insertions, etc.).  Willing to make search efficient but not willing to modify the Maude engine.
  • 29. MEMORIES AND VIEWS Memory updates Local to Global In the following abbreviates
  • 39. MORE ANNOYANCES... x := 1 Maude> search P =>* Q . ... States: 10!? x := 2P =
  • 40. x|->0 =============== || --------------- x:=1; || x:=2; x|->0 =============== x|->1 || --------------- skip || x:=2; x|->0 =============== || x|->2 --------------- x:=1 || skip x|->0 =============== x|->1 || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || x:=2; x|->2 =============== || --------------- x:=1 || skip x|->1 =============== || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || skip x|->2 =============== x|->1 || --------------- skip || skip x:=1; x:=1; x:=1; x:=2; x:=2; x:=2; commit commit commit commit commitcommit x|->2 =============== || --------------- skip || skip state Shared memory Thread buffer Thread program
  • 41. x|->0 =============== || --------------- x:=1; || x:=2; x|->0 =============== x|->1 || --------------- skip || x:=2; x|->0 =============== || x|->2 --------------- x:=1 || skip x|->0 =============== x|->1 || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || x:=2; x|->2 =============== || --------------- x:=1 || skip x|->1 =============== || x|->2 --------------- skip || skip x|->1 =============== || --------------- skip || skip x|->2 =============== x|->1 || --------------- skip || skip x:=1; x:=1; x:=1; x:=2; x:=2; x:=2; commit commit commit commit commitcommit x|->2 =============== || --------------- skip || skip state Shared memory Thread buffer Thread program Usual state space with SC
  • 42. while true do x := 0 Maude> search P =>* Q . Zzz... P = MORE ANNOYANCES...
  • 43. x|->0 ==================== -------------------- while(true) do x:=0 x|->0 ==================== -------------------- x:=0; while(true) do x:=0 while(true) x:=0; x|->0 ==================== x|->0 -------------------- while(true) do x:=0 x|->0 ==================== x|->0 -------------------- x:=0; while(true) do x:=0 while(true) x|->0 ==================== x|->0 x|->0 -------------------- while(true) do x:=0 while(true) x:=0; commit commit commit ...
  • 45. Partial Order Reduction Techniques  Partial Orders [Alglave et al. @ CAV 2013]  Persistent Sets [Linden&Wolper @ TACAS 2013]  Ample sets (via SPIN) [Jonson @ CAN2009] Approximation/abstraction techniques  Predicate abstraction [Dan et al. @ SAS 2013]  Bounded context-switches [Abdulla et al. @ TACAS 2012]  Single-buffer semantics [Atig et al. @ CAV 2011]  Buffers-as-sets abstraction [Kuperstein et al. @ PLDI 2011]  Bounded buffers [Kuperstein et al. @ FMCAD 2011] Other  SAT/BMC [Burckhardt et al @ CAV 6/7/8, Gopalakrishnan et al. @ CAV 04]  Buffer automata [Linden&Wolper @ SPIN2010, TACAS 2013]  Monitors [Burnim et al. @ TACAS 2011, Burckhardt&Musuvathi @ CAV 2008] TEN+ YEARS OF RESEARCH Equational abstractions? [Meseguer&Palomino&Martí-Oliet @ TCS 2008] Partial-order reduction? [Farzan&Meseguer @ TERMGRAPH 2006] Search strategies? [Martí-Oliet&Meseguer&Verdejo @ WRLA 2004]
  • 46. SOME SIMPLE APPROXIMATIONS FOR TSO Disclaimer: proof-of-concepts, for the “good” ones see the above cited papers.
  • 47. ONE OF OUR ANOYANCES while true do x := 0 Maude> search P =>* Q . Zzz..
  • 48. BUFFERS AS SETS OF UPDATES Abstract buffers as sets of updates:  Make ACI1 (i.e. buffer becomes sets of updates);  Make commit non-deterministic (usual+no effect);  Make evaluation of expressions non-deterministic. You get an over-approximation:  Finite state space;  Preservation of reachability properties.  (Possibly) some “spurious” behaviours;
  • 49. Dekker Peterson Lamport Szymanski 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 No reduction Buffers-as-Sets Buffers-as-Ordered-Maps Force-Flush MORE STATES
  • 50. BUFFERS AS ORDERED MAPS Approximation that  Guarantees finite state space;  Introduces some executions;  Preserves some reachability properties??? (under investigation)
  • 52. x|->0 , y |->0 =============== || --------------- x:=1; || wait(...) y:=1; || x:=2 || x|->0 , y |->0 =============== x|->1 || --------------- y:=1; || wait(...) x:=2; || x|->0 , y |->0 =============== x|->1 || y|->1 || --------------- x:=2; || wait(...) x|->0 , y |->0 =============== x|->1 || y|->1 || x|->2 || --------------- skip || wait(...) x|->1 , y |->0 =============== || --------------- y:=1; || wait(...) x:=2; || x|->1 , y |->0 =============== y|->1 || --------------- x:=2; || wait(...) x|->1 , y |->0 =============== y|->1 || x|->2 || --------------- skip || wait(...) x|->1 , y |->1 =============== || --------------- x:=2; || wait(...) x|->1 , y |->1 =============== x|->2 || --------------- skip || wait(...) x|->2 , y |->1 =============== || --------------- skip || wait(...) commit commitcommit commit commit commit x|->0 , y |->0 =============== y|->1 || x|->2 || --------------- skip || wait(...) wait! ONE “SPURIOUS” EXECUTION x|->0 , y |->1 =============== y|->1 || --------------- skip || wait(...) commit
  • 53. Dekker Peterson Lamport Szymanski 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 No reduction Buffers-as-Sets Buffers-as-Ordered-Maps Force-Flush REDUCTIONS
  • 54. FORCE-FLUSH APPROXIMATION Under-approximation that  Does not guarantee finite state space ;  Some behaviours may be lost;  Does not introduce spurious behaviours. (up to some equivalence: stuttering and depending on the state observations).
  • 55. M =============== x|->u || ... || x|->v || --------------- S || T M ◦ x|->u =============== ... || x|->v || --------------- S || T NO “SPURIOUS” EXECUTION M =============== x|->u || ... || || --------------- x:=v; S || T M ◦ x|->u =============== ... || || --------------- x:=v; S || T commit x:=v x:=v (up to some equivalence: stuttering and depending on the state observations).
  • 56. Dekker Peterson Lamport Szymanski 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 No reduction Buffers-as-Sets Buffers-as-Ordered-Maps Force-Flush REDUCTIONS
  • 58. AMPLE SETS Main idea  Explore only a subset ample(s) of the succesors of s...  ...such that ample(s): C0: ample(s) empty only if s is a deadlock; C1: ample(s) contains invisible actions; C2: no transition that is dependent on a transition in ample(s) occurs in the original system without a transition in ample(s) occurring first; C3: no action outside ample(s) is delayed forever.  You will get a stutter equivalent transition system.
  • 59. SIMPLE POR FOR TSO Simple heuristic: assignments x := u are independent of actions of other threads since their effect is local (on the buffer). They are also invisible unless one wants to observe buffers or programs.
  • 60. Dekker Peterson Lamport Szymanski 0 100 200 300 400 500 600 700 800 900 1000 No reduction Partial-Order Reduction REDUCTIONS (verification)
  • 62. DIRECTED MODEL CHECKING Main idea  Replace the exploration algorithm (NDFS/BFS) by a “guided” algorithm (A*, Best-First, etc.)  Domain/property-based “heuristic” functions to rank states or executions “Heuristics for model checking Java” [Groce&Visser]  Promote interleavings (we think “sequentially”)  Promote code coverage Done for JPF, SPIN, etc.
  • 63. x|->0 , y|->0 =============== || --------------- x:=1; || y:=1; y==0? || x==0? x|->0 , y|->0 =============== x->1 || --------------- y==0? || y:=1; || x==0? x|->0 , y|->0 =============== || y->1 --------------- x:=1 || x==0? y==0? || x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || x==0? x|->1 , y|->0 =============== || --------------- y==0? || y:=1; || x==0? x|->0 , y|->1 =============== || --------------- X:=1 || x==0? y==0? || x:=1; x:=1; y:=1; y:=1;flush flush ... ... x|->0 , y|->0 =============== x->1 || y->1 --------------- cs || x==0? x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || cs
  • 64. x|->0 , y|->0 =============== || --------------- x:=1; || y:=1; y==0? || x==0? x|->0 , y|->0 =============== x->1 || --------------- y==0? || y:=1; || x==0? x|->0 , y|->0 =============== || y->1 --------------- x:=1 || x==0? y==0? || x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || x==0? x|->1 , y|->0 =============== || --------------- y==0? || y:=1; || x==0? x|->0 , y|->1 =============== || --------------- X:=1 || x==0? y==0? || x:=1; x:=1; y:=1; y:=1;flush flush 0 0 0 2 1 0 0 0 1 ... ... x|->0 , y|->0 =============== x->1 || y->1 --------------- cs || x==0? x|->0 , y|->0 =============== x->1 || y->1 --------------- y==0? || cs 2 2 Count number of non-empty buffers
  • 65. Dekker Peterson Lamport Szymanski 0 50 100 150 200 250 300 350 400 450 Breadth-First Search Best-First + "number of non-empty buffers" heuristic Best-First + "number of pending writes" heuristic Best-First + "number of inconsistent pending writes" heuristic REDUCTIONS (bug-finding)
  • 67. I would say yes. Worth investigating Can we efficiently verify concurrent programs under relaxed memory models in Maude?
  • 68. Beyond TSO: PSO, RMO, etc.1 2 FUTURE WORK? Other languages/primitives: see e.g. KernelC/x86-TSO in K [Serbanuta] 3 Proof techniques (with Maude)
  • 71. [Linden&Wolper @ TACAS 2013] Alexander Linden, Pierre Wolper: A Verification-Based Approach to Memory Fence Insertion in PSO Memory Systems. TACAS 2013: 339-353 [Dan&MMeshman&Vechev&Yahav @ SAS 2013] Andrei Marian Dan, Yuri Meshman, Martin T. Vechev, Eran Yahav: Predicate Abstraction for Relaxed Memory Models. SAS 2013: 84-104 [Alglave et al. @ CAV 2013] Jade Alglave, Daniel Kroening, Michael Tautschnig: Partial Orders for Efficient Bounded Model Checking of Concurrent Software. CAV 2013: 141-157 [Abdulla&Atig&Chen&Leonardsson&Rezine @ TACAS 2012] Abdulla, P.A., Atig, M.F., Chen, Y.-F., Leonardsson, C., Rezine, A.: Counter- Example Guided Fence Insertion under TSO. In: TACAS 2012. LNCS, vol. 7214 (2012) [Atig&Bouajjani&Parlato @ CAV 2011] Atig, M.F., Bouajjani, A., Parlato, G.: Getting Rid of Store-Buffers in TSO Analysis. In: Gopalakrishnan, G., Qadeer, S. (eds.) CAV 2011. LNCS, vol. 6806 (2011) [Kuperstein&Vechev&Yahav @ PLDI 2011] Kuperstein, M., Vechev, M., Yahav, E.: Partial-coherence abstractions for relaxed memory models. In: PLDI 2011 (2011) REFERENCES (1)
  • 72. [Burnim&Sen&Stergiou @ TACAS 2011] Jacob Burnim, Koushik Sen, Christos Stergiou: Sound and Complete Monitoring of Sequential Consistency for Relaxed Memory Models. TACAS 2011: 11-25 [Burnim&Sen& C. Stergiou @ TACAS 2011] J. Burnim, K. Sen, and C. Stergiou. Sound and complete monitoring of sequential consistency in relaxed memory models. In TACAS, 2011. [Kuperstein&Vechev&Yahav @ FMCAD 2011] M. Kuperstein, M. Vechev, and E. Yahav. Automatic inference of memory fences. In FMCAD, 2011. [Linedn&Wolper @ SPIN 2010] A. Linden and P. Wolper. An automata-based symbolic approach for verifying programs on relaxed memory models. In SPIN, 2010. [Jonson @ CAN2009] Jonsson, B.: State-space exploration for concurrent algorithms under weak memory orderings: (preliminary version). SIGARCH Comput. Archit. News 36, 65–71 (2009) [Burckhardt&Musuvathi @ CAV 2008] Burckhardt,S.,Musuvathi,M.: Effective Program Verification for Relaxed Memory Models. In: Gupta, A., Malik, S. (eds.) CAV 2008. LNCS, vol. 5123, pp. 107–120. Springer, Heidelberg (2008) REFERENCES (2)
  • 73. [Burckhardt&Alur&Martin @ CAV 2007] Burckhardt, S., Alur, R., Martin, M.M.K.: Checkfence: checking consistency of concurrent data types on relaxed memory models. In: ACM SIGPLAN 2007 Conference on Programming Lan- guage Design and Implementation (2007) [Burckhardt&Alur&Martin @ CAV 2006] Burckhardt,S.,Alur,R.,Martin,M.M.K.: Bounded Model Checking of Concurrent Data Types on Relaxed Memory Models: A Case Study. In: CAV 2006. LNCS 4144. (2006) [Gopalakrishnan&Yang&Sivaraj @ CAV 2004] Gopalakrishnan, G., Yang, Y., Sivaraj, H.: QB or not QB: An efficient execution verification tool for memory orderings. In: CAV 2004. LNCS, vol. 3114 (2004) [Park&Dill @ PAA 1995] Park, S., Dill, D.L.: An executable specification, analyzer and verifier for rmo (relaxed memory order). In: SPAA 1995: Proceedings of the Seventh Annual ACM Symposium on Parallel Algorithms and Architectures, pp. 34–41. ACM, New York (1995) REFERENCES (3)
  • 74. [Meseguer&Palomino&Martí-Oliet @ TCS 2008] José Meseguer, Miguel Palomino, Narciso Martí-Oliet: Equational abstractions. Theor. Comput. Sci. 403(2-3): 239-264 (2008) [Farzan&Meseguer @ TERMGRAPH 2006] Azadeh Farzan, José Meseguer: Partial Order Reduction for Rewriting Semantics of Programming Languages. Electr. Notes Theor. Comput. Sci. 176(4): 61-78 (2007) [Rodríguez 2009 @ WRLA 2009] Rodríguez, D.E.: Combining techniques to reduce state space and prove strong properties. In: WRLA. Volume 238(3) of ENTCS. (2009) 267 – 280 [Lluch&Meseguer&Vandin @ ICFEM 2012] Alberto Lluch-Lafuente, José Meseguer, Andrea Vandin: State Space c-Reductions of Concurrent Systems in Rewriting Logic. ICFEM 2012: 430-446 [Martí-Oliet&Meseguer&Verdejo @ WRLA 2004] Narciso Martí-Oliet, José Meseguer, Alberto Verdejo: Towards a Strategy Language for Maude. Electr. Notes Theor. Comput. Sci. 117: 417-441 (2005) [Groce&Visser @ STTT 2004] Alex Groce, Willem Visser: Heuristics for model checking Java programs. STTT 6(4): 260-276 (2004) REFERENCES (4)