Understanding Code with Valgrind

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Understanding Code with Valgrind

• Beware of bugs in the above code
• I have only proved it correct, not tried it.
• Donald E Knuth
• Madhu M Kurup
• technical yahoo!
• Yahoo! Inc.
• mmk at yahoo dash inc dot com

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What is Valgrind

• Linux, x86, program analyzer
• Advantages
• powerful
• no recompiles, just binaries
• any language (!)
• extensible, configurable
• free, GPL'd goodness
• Speed slowdown

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How does it work

• Synthetic CPU
• Per instruction execution
• Host System
• Controlled
• Memory
• leaks, overflows, et all
• Threading
• posix library
• Caching
• L1/L2 cache info (!)

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What are the existing skins

• MemCheck
• Heavy duty memory checker
• AddrCheck
• Faster, cheaper
• Cachegrind
• Caching info
• Helgrind
• Thread semantics
• Others

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Live Example

• Where and what do you want to fix today?

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Other features

• Callgraphs
• Multiple other patches
• Open file descriptors
• Suppressions
• Selective understanding
• Ignore System libs
• Yes, bugs
• /dev/random

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Future Thoughts

• GUIs
• Simulation
• instructions
• ioctls
• bugs, more bugs
• Net/FreeBSD
• Moore's Law

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End of Transmission

• Thanks Questions?
• URLs and Lists
• Main http//valgrind.kde.org/
• Code http//webcvs.kde.org/cgi-bin/cvsweb.cgi/val
  grind/
• GUI's http//valgrind.kde.org/related.html
• Dev http//lists.sourceforge.net/lists/listinfo/v
  algrind-developers
• Users http//lists.sourceforge.net/lists/listinfo
  /valgrind-users
• http//ooextras.sourceforge.net/