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NGEN PDB Generation for Profiling

8 posts · Dec 2012 – Sep 2015

What this trail covers

This feature thread tracks the generation and use of NGEN PDBs for profiling managed applications on Windows 8 and later. It addresses the challenge of understanding profiling reports when NGEN'd modules lack symbols, by providing a step-by-step process to create NGEN PDBs using the Native Image Generator (ngen.exe) and integrate them into the Visual Studio profiler's symbol path. This enables the display of function names and source code locations in profiling reports, significantly improving the debugging and performance analysis of managed code.

All Microsoft trails
  1. Concurrency Visualizer for Visual Studio 2015 is now available on the galleryThe Concurrency Visualizer for Visual Studio 2015 is now available on the Visual Studio Gallery. Command line collection tools are available on the Microsoft Download Center. This update is required for users upgrading from previous Visual Studio versions (2010, 2012, 2013) to Visual Studio 2015. The Concurrency Visualizer supports Windows Desktop applications only, not ASP.NET or Universal Windows Projects.
  2. Debugging Optimized CodeThis post details how to debug optimized code, which is challenging due to compiler optimizations like dead code elimination, loop optimizations, and inline expansion. It explains that variable inspection and breakpoint hitting can be unreliable. For C++, the /Zo flag and selective de-optimization using #pragma optimize("",off) are suggested. For .NET, the "Suppress JIT optimizations on module load" option in Visual Studio is discussed, along with its implications. The post also recommends using the Disassembly window to step through actual machine code when debugging optimized builds.
  3. Understanding symbol files and Visual Studio’s symbol settingsThis post details the fundamental concepts of symbol files (.pdb) and their importance for debugging and diagnostic tools in Visual Studio. It explains how symbol files are generated, what they contain, and why they are necessary for correlating machine code to source code. The post outlines Visual Studio's default symbol loading behavior, how to identify when symbols are not loaded, and provides a comprehensive guide to configuring Visual Studio's symbol settings, including symbol file locations, caching, and automatic loading options. It also covers manual symbol loading techniques and troubleshooting common symbol loading issues.
  4. View Source in the CPU Usage toolIntroduced the 'View Source' functionality in the CPU Usage tool (Update 3 of Visual Studio 2013), enabling direct navigation from a function in the call tree to its source code. This feature supports C#/VB, C++, and JavaScript, and provides guidance on when it might be disabled (missing PDBs, missing source files, lack of line-level info in PDBs, generated code, external libraries). It specifically mentions the scenario of NGen modules and the need for manually generated NGen PDBs with line information for profiling.
  5. .NET Remote Symbol Loading Changes in Visual Studio 2012 and 2013This post details changes in .NET remote symbol loading for Visual Studio 2012 and 2013. VS2010 required PDBs on the remote machine. VS2012 and 2013 load PDBs locally by default. It introduces registry exceptions for specific remote PDB loading scenarios and the /FallbackLoadRemoteManagedPdbs flag in VS2013 Update 2.
  7. How to profile a XAML Windows Store AppThis post details how to use the Visual Studio CPU profiler to identify performance bottlenecks in XAML Windows Store Apps. It explains CPU sampling, collecting data, analyzing the summary page, function details, and call tree views. It also provides a code example demonstrating performance improvements by re-using storyboards and storing objects as properties. The post highlights that even non-CPU bound applications can benefit from profiling to find expensive code paths.
  8. VS2012 Update 2 Brings Symbol Improvements to Profiler and IntelliTraceVisual Studio 2012 Update 2 applies the symbol loading logic from Update 1 to IntelliTrace scenarios (live debugging and .iTrace file analysis) and performance analysis of Windows Store apps and CPU sampling profiling on Windows 8. This includes a cancellation dialog for symbol loading and improved manual symbol loading through the Modules window, making it cancellable and benefiting from caching.
  9. More on Symbol Improvements in VS2012 Update 1This post details specific improvements to symbol loading in Visual Studio 2012 Update 1: making symbol loading fully cancellable, implementing recording of symbol misses to avoid re-searching paths within a VS session, and enhancing caching for symbols downloaded from network shares (limiting to 5 versions per PDB) and improving handling of invalid cache paths. The Modules window now indicates cancelled loads, and the Symbol Load Information dialog shows reasons for skipped symbols.
  10. Creating NGEN PDBs for Profiling ReportsThis post details a four-step process for generating NGEN PDBs to resolve issues with profiling managed applications on Windows 8 where NGEN'd modules appear as '[NI module name]' in reports due to missing PDB files. It explains the background of the issue related to the profiler's technology on Windows 8, and provides detailed instructions for: 1. Locating the NI module's path in the profiler report. 2. Creating the PDB using ngen.exe, with options for including line-level information. 3. Adding the generated PDBs to the Visual Studio symbol path. 4. Reopening the profiler report to see function names instead of '[NI module name]'. It also notes that PDBs need to be regenerated if modules are updated and mentions an update in Visual Studio 2013 for automatic NGEN PDB generation.