Pentium Performance Unlocked

A visual tool goes beyond profiling to provide instruction-level tuning tips for 486 or Pentium platforms

Robert L. Hummel

Rising user expectations of sizzling applications performance have put programmers back in the code-optimization hot seat. Fortunately, this doesn't mean you'll have to dust off your assembler. Intel has introduced VTune, a Windows-based visual-tuning environment for the x86 architecture.The tool provides a visual display of the CPU resources being consumed by all active software on Windows 3.1 and Windows 95 systems. It identifies the sections of code that are using substantial CPU processing time, not only in the application being tuned, but in the OS and device drivers as well. Time spent in system and user modes and for 32-bit, 16-bit, and V86 applications is also displayed.

With VTune, you can identify and troubleshoot code hot spots. Double-clicking on a resource spike brings up the Hotspots window, a low-level view of the sections of code within that module. If you double-click again, the Source Viewer brings up your source code. The tool requires no source code changes. If source code isn't available, a built-in disassembler creates listings from object files.Regardless of the programming language, including assembly languag e, VTune displays the line numbers and percentage of CPU time spent executing each active code statement. VTune flags possible trouble, including instruction sequences that result in penalty conditions and poor instruction pairing.

VTune goes beyond simply reporting trouble. Context-sensitive tuning tips are available as on-line help. The program is language-independent and works with industry-standard compilers . But if you program in C, the C Tuning Coach identifies tuning opportunities in your source code and validates your current optimizations.

Improvements can be dramatic. "After two days of work with these tools, we were able to boost display performance [of our Windows application] 12 times higher," says Udi Noach, R&D Manager at Ampol Technologies, an Israeli company. "[VTune has] helped us detect precious idle system time that we could exploit."Using the built-in scripting interface, you can perform automated performance analysis of all the software executing on your system.VTune supports 486 and Pentium processors. Intel plans support for the Pentium Pro (P6) processor.

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VTune Displays Details

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VTune can display details of the Pentium's dual-pipeline architecture, showing actual instruction pairing and penalty information.