Intel® VTune™ Profiler User Guide

User Guide

Contents

Profile KVM Kernel Modules from the Host

If you are a system developer and interested in the performance analysis of a guest Linux* system including KVM modules, consider using this usage mode:
  1. Prepare your system for analysis:
    1. Copy the
      /proc/kallsyms
       and
      /proc/modules
       files from a guest OS to a host file system to have KVM guest OS symbols resolved.
    2. Copy any guest OS’s modules of interests (
      vmlinux
       and any
      *.ko
       files) from a guest OS and save them to a
      [guest]
       folder on the host file system.
  2. Click the
    Configure Analysis
     button on the
    VTune
    Profiler
     toolbar.
    The
    Configure Analysis
     window opens.
  3. Make sure to select the
    Local Host
     target system in the
    WHERE
     pane and configure the required target type in the
    WHAT
     pane.
    By default, the
    Launch Application
     target type is selected.
    If you select the
    Attach to Process
     target type, specify the
    qemu-kvm
     process to attach to.
    Alternatively, you may specify the PID of the
    qemu-kvm
     process. To determine the PID, enter:
    $ ps aux | grep kvm
  4. In the
    Advanced
     section of the
    WHAT
     pane, select the
    Analyze KVM guest OS
     option and enter paths to the local copies of the guest
    /proc/kallsyms
     and
    /proc/modules
     files; for example:
  5. Click the
    Search Binaries
     button on the bottom right.
    The
    Binary/Symbol Search
     dialog box opens.
  6. Add a local path to a
    [guest]
     folder where all modules copied from the guest OS reside.
    For example, if your
    [guest]
     folder is located in
    /home/vtune
    , specify
    /home/vtune
     as a search directory:
  7. Click
    OK
     to save your changes.
  8. In the
    HOW
     pane, select a required analysis type.
    For KVM guest OS profiling, you may choose analysis types using Perf*-based EBS data collection: Hotspots (hardware event-based sampling mode), System Overview, or configure your own custom analysis.
  9. Click the
    Start
     button at the bottom to run the analysis.
When you run the analysis, the
VTune
Profiler
 collects the data on both host and guest OS and displays merged statistics in the result. Guest OS modules have the
[guest]
postfix in the grid. For example:
Focus on the
Platform
 tab to analyze your code performance on the guest OS and correlate this data with CPU, GPU, power, hardware event metrics and interrupt count at each moment of time. If you enabled the kvm Ftrace event collection for your target, you can also monitor the statistics for KVM kernel module:
Limitations
  • In this mode, the
    VTune
    Profiler
     collects data only on the kernel space modules on the KVM guest OS. Data on user space modules shows up in the
    [Unknown]
    node and includes only high-level statistics.
  • Call stack data is not collected for this type of profiling.

Product and Performance Information

1

Performance varies by use, configuration and other factors. Learn more at www.Intel.com/PerformanceIndex.