CIRM - Dynamic Error Detection Peter Pirkelbauer Center for Applied - - PowerPoint PPT Presentation

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CIRM - Dynamic Error Detection Peter Pirkelbauer Center for Applied - - PowerPoint PPT Presentation

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CIRM - Dynamic Error Detection Peter Pirkelbauer Center for Applied Scientific Computing (CASC) Lawrence Livermore National Laboratory This work was funded by the Department of Defense and used elements at the Extreme Scale Systems Center, at

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CIRM - Dynamic Error Detection

Peter Pirkelbauer

Center for Applied Scientific Computing (CASC) Lawrence Livermore National Laboratory

This work was funded by the Department of Defense and used elements at the Extreme Scale Systems Center, at Oak Ridge. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 Lawrence Livermore National Laboratory, P . O. Box 808, Livermore, CA 94551 UCRL-LLNL-PRES-504931 Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 1 / 22

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Overview

1

Code Instrumentation and Runtime Monitor Motivation Sequential Codes Parallel Codes Results Summary and Future Work

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 2 / 22

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SLIDE 3

Example

Return Invalid Pointer

int∗ foo() { int res = ...; return &res; }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 3 / 22

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Runtime Error Detection for C, C++03 and UPC

Motivation Cost of software bugs is significant

estimated at 0.6% of GDP [National Institute of Standards & Technology, 2002]

Bug Detection Tools

Valgrind, Insure++, Purify, ...

Error Detection Benchmarks Suites

RTED [Luecke et al., 2009b]

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 4 / 22

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Bug Detection Tools

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 5 / 22

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Sequential Runtime Error Categories

Detected Runtime Errors C-style errors

  • ut-of-bounds accesses, uninitialized variables, tangling pointers,

arithmetic overflow/underflow

C-library functions

arguments violate precondition

Mismatches in memory allocation and deallocation methods

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 6 / 22

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SLIDE 7

ROSE Overview

C/UPC/C++ S

  • urceC
  • de

Analy zed/ T ransform edC

  • de

ED GFront-end/ OpenFortranParser

IR (AS T)

Binary D isassem bler Unparser

ROSE Compiler Infrastructure 2009Winner www.roseCompiler.org Transformations ROSE-based Tools Analyses Optimizations

Fortran/OpenMP Software BinaryCode

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 7 / 22

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ROSE-CIRM Architecture (Sequential)

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 8 / 22

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SLIDE 9

Code Instrumentation: Scope and Pointer Tracking

Original Code

int∗ foo() { int res = ...; return &res; }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 9 / 22

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Code Instrumentation: Scope and Pointer Tracking

Instrumented Code

int∗ foo() { int res = ...; cirmCreateVar(&res, "int", cirmInitialized); return &res; }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 9 / 22

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SLIDE 11

Code Instrumentation: Scope and Pointer Tracking

Instrumented Code

int∗ foo() { cirmScopeGuard guard; int res = ...; cirmCreateVar(&res, "int", cirmInitialized); int∗ ptr = &res; return ptr; }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 9 / 22

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Code Instrumentation: Scope and Pointer Tracking

Instrumented Code

int∗ wrapped_foo() { cirmScopeGuard guard; int res = ...; cirmCreateVar(&res, "int", cirmInitialized); int∗ ptr = &res; return ptr; } int∗ foo() { int∗ res = wrapped_foo(); cirmValidatePtr(res); return res; }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 9 / 22

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Unified Parallel C (UPC)

UPC extends C99 Partitioned global address space (PGAS) Language constructs for parallelism

shared pointers, parallel for loop, memory consistency model

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 10 / 22

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Parallel Runtime Error Categories

Detected Runtime Errors C-style error in the UPC shared space

  • ut-of-bounds accesses, uninitialized variables, tangling pointers,

arithmetic overflow/underflow

Not Yet Implemented Parallelism related errors

deadlocks, livelocks, race conditions

UPC-library functions arguments violate precondition

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 11 / 22

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CIRM Runtime System (Parallel)

Instrumented Code

shared[] int ∗values = upc_all_alloc(...); cirmCreateHeap(values, ...); cirmInitVariable(&values); cirmAccessArray(&values[MYTHREAD], &values[0]); // bounds check values[MYTHREAD] = ...; cirmInitVar(&values[MYTHREAD], ...);

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 12 / 22

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CIRM Runtime System (Parallel)

Instrumented Code

shared[] int ∗values = upc_all_alloc(...); cirmCreateHeap(values, ...); cirmInitVariable(&values); cirmAccessArray(&values[MYTHREAD], &values[0]); // bounds check values[MYTHREAD] = ...; cirmInitVar(&values[MYTHREAD], ...);

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 12 / 22

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Runtime Monitor Coordination - Concurrent Access (1)

Instrumented Code

// shared int val; if (MYTHREAD==0) { val = compute(...); cirmInitVariable(&val, ...); } cirmEnterBarrier(); upc_barrier; cirmExitBarrier(); cirmAccessVar(&val, ...); printf("%d\n", val);

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 13 / 22

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Runtime Monitor Coordination - Concurrent Access (2)

Instrumented Code

// shared int val; if (MYTHREAD==0) { val = compute(...); cirmInitVariable(&val, ...); } cirmAccessVar(&val, ...); printf("%d\n", val);

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 14 / 22

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Runtime Monitor Coordination - Early Release

Instrumented Code

shared[] int ∗values = upc_all_alloc(...); values[idx] = compute(idx); // upc_barrier; if (MYTHREAD == 0) { upc_free(ptr); }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 15 / 22

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Runtime Monitor Coordination - Early Release

Instrumented Code

shared[] int ∗values = upc_all_alloc(...); cirmArrayAccess(&values[0] &values[idx]); values[idx] = compute(idx); cirmInitVariable(&values[...], ...); // upc_barrier; if (MYTHREAD == 0) { cirmEnterHeapUpdate(); cirmFreeMem(&ptr); upc_free(ptr); cirmExitHeapUpdate(); }

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 15 / 22

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Address Abstraction Implemented for GCCUPC [Funck, 2006]

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 16 / 22

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Tests: Error Detection Benchmark (C++03)

Luecke et al.: RTED Benchmark Suite for C++03 [Luecke et al., 2009b] Category Number Correctly Identified

  • f tests

(in percent) Allocation deallocation errors 109 104 (95%) Array index out of bound 332 329 (99%) Floating point errors 17 17 (100%) Input output errors 28 18 (64%) Memory leaks 42 38 (90%) Pointer errors 157 155 (99%) String errors 40 40 (100%) Uninitialized variables 221 213 (96%)

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 17 / 22

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Tests: Error Detection Benchmark (UPC)

Luecke et al.: RTED Benchmark Suite for UPC [Luecke et al., 2009a] Category Number Correctly Identified

  • f tests

(in percent) Out of bounds accesses (indices) 726 685 (94%) Out of bounds accesses (pointers) 160 150 (94%) Uninitialized memory reads 64 62 (97%) Dynamic memory handling related 10 10 (100%)

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 18 / 22

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Tests: Performance

El-Ghazawi et al.: Distributed Shared Memory Programming [El-Ghazawi et al., 2003]

80 elements per dimension 8 Threads Intel X5680 6x2 cores @ 3.3Ghz 24GByte Memory Red Hat Linux 5.6 gccupc 4.5.1.2, g++ 4.1.2

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 19 / 22

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Improving Performance

Static Analysis Comes to Rescue Reaching definition → eliminates local initialization checks Local escape analysis → eliminates variable tracking Interval analysis → eliminates local bounds checks . . . Integrate Checking into Instrumented Code Implemented arithmetic overflow/underflow checks − → performance overhead is 20%

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 20 / 22

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Summary and Future Work

Integrate static analysis to improve sequential checks Develop static analysis to accelerate checking parallel codes

absence of race conditions in certain code segments to use less expensive checking mechanisms reduce communication overhead

1Runtime Detection of C-Style Errors in UPC Code.

[Pirkelbauer et al., 2011]

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 21 / 22

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Thank You!

Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 22 / 22

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SLIDE 28

Tarek El-Ghazawi, William Carlson, Thomas Sterling, and Katherine Yelick. UPC: Distributed Shared-Memory Programming. Wiley-Interscience, 2003. Gary Funck. GPC/UPC 4.0, "flexible heap" design overview. Technical report, Intrepid Technology Inc., Sep 2006. Glenn R. Luecke, James Coyle, James Hoekstra, Marina Kraeva, Ying Xu, Elizabeth Kleiman, and Olga Weiss. Evaluating error detection capabilities of UPC run-time systems. In Third Conference on Partitioned Global Address Space Programing Models, PGAS ’09, pages 7.1 – 7.4, New York, NY, USA, 2009. ACM. Glenn R. Luecke, James Coyle, James Hoekstra, Marina Kraeva, Ying Xu, Mi-Young Park, Elizabeth Kleiman, Olga Weiss, Andrew Wehe, and Melissa Yahya. The importance of run-time error detection. In Third Parallel Tools Workshop, 2009. National Institute of Standards & Technology. The Economic Impacts of Inadequate Infrastructure for Software Testing. RTI (Health, Social, and Economics Research), May 2002. Peter Pirkelbauer, Chunhua Liao, Thomas Panas, and Daniel Quinlan. Runtime detection of C-style errors in UPC code. In 5th Conference on Partitioned Global Address Space Models (PGAS), 2011. Peter Pirkelbauer (LLNL) Dynamic Error Detection TAMU April 28, 2012 22 / 22