Intel® Itanium® Prozessoren

Prepare Applications for Optimization on 64-Bit Intel® Architecture


Challenge

Prepare applications for optimization on the Intel® Itanium® processor family. The first issue in getting high performance code on Itanium-based systems is to get the code ported or written to run correctly in the 64-bit environment. It is not uncommon for code that functions correctly in a 32-bit environment to have latent bugs that will be exposed when the code is moved to a 64-bit environment.

  • performance
  • Intel® Itanium® Prozessoren
  • Perform Code Timing and Profiling for Linux on 64-Bit Architecture


    Challenge

    Measure the time a program and its functions take to execute as part of the diagnosis phase of performance optimization. Such measurements are extremely valuable as a simple means to become familiar with how an application behaves during execution.


    Solution

    Use either the Linux time command or the clock function in the C library, and profile the application during compilation. The time command is used as follows:

    prompt> time

    It gives the following information:

  • Linux*
  • performance
  • Intel® Itanium® Prozessoren
  • Perform Back-End Bubble Root-Cause Analysis on 64-Bit Intel® Architecture


    Challenge

    Identify the root cause of a back-end processor bubble on the Intel® Itanium® processor. A separate item, How to Identify Back-End Bubbles on 64-Bit Intel® Architecture, shows how to use the Intel® VTune™ Performance Analyzer to identify a bubble. In order to resolve this performance issue, the root cause of the bubble must be determined.

  • performance
  • Intel® Itanium® Prozessoren
  • Identify Bank/Address Conflicts on 64-Bit Intel Architecture


    Challenge

    Identify and locate conflicts in the EXE pipeline. Microprocessor cache architectures frequently have access structures that allow for very low latencies, but in some circumstances, this is not applicable. You encounter one of the more common causes of restrictions when the program needs to load multiple pieces of data at the same time. This means that the compilers must generate code that issues two load instructions on the same cycle.

  • Memory Access
  • Intel® Itanium® Prozessoren
  • Identify Back-End Bubbles on 64-Bit Intel® Architecture


    Challenge

    Identify a processor back-end bubble on the Intel® Itanium® processor. A 'bubble' is defined as any delay in the processor. The 'back end' is the place where instructions are retired when they are complete. There are five main causes of bubbles in the Itanium 2 processor:

  • performance
  • Intel® Itanium® Prozessoren
  • How to Perform Back-End Bubble Root-Cause Analysis on 64-Bit Intel® Architecture


    Challenge

    Identify the root cause of a back-end processor bubble on the Intel® Itanium® 2 processor. A separate item, How to Identify Back-End Bubbles on 64-Bit Intel® Architecture, shows how to use the Intel® VTune™ Performance Analyzer to identify a bubble. In order to resolve this performance issue, the root cause of the bubble must be determined.

  • Intel® Itanium® Prozessoren
  • How to Identify Back-End Bubbles on 64-Bit Intel® Architecture


    Challenge

    Identify a processor back-end bubble on the Intel® Itanium® 2 processor. A 'bubble' is defined as any delay in the processor. The 'back end' is the place where instructions are retired when they are complete. There are five main causes of bubbles in the Itanium 2 processor:

  • Intel® Itanium® Prozessoren
  • Functional Unit Stalls on 64-Bit Intel® Architecture


    Challenge

    Minimize inefficiencies due to functional-unit latency stalls. Computers require functional-unit latency stalls to ensure that results are computed correctly. In a chain of instructions, the output of one instruction may be used as the input of another. If there are an insufficient number of instructions (cycles) between the two to absorb the operational latency of generating the data, the second operation must stall until the data is ready. This is called a “scoreboarded” stall.

  • Stall Analysis
  • Intel® Itanium® Prozessoren
  • Intel® Itanium® Prozessoren abonnieren