Intel® VTune™ Profiler User Guide

User Guide

Contents

Sampling Drivers

Intel® VTune™
Profiler
 uses kernel drivers to enable the hardware event-based sampling.
VTune
Profiler
 installer automatically uses the Sampling Driver Kit to build drivers for your kernel with the default installation options. If the drivers were not built and set up during installation (for example, lack of privileges, missing kernel development RPM, and so on),
VTune
Profiler
 provides an error message and, on Linux* and Android* systems, enables driverless sampling data collection based on the Linux Perf* tool functionality, which has some analysis limitations for a non-root user.
VTune
Profiler
 also automatically uses the driverless mode on Linux when hardware event-based sampling collection is run with stack analysis, for example, for Hotspots or Threading analysis types.
If not used by default, you may still enable a driver-based sampling data collection by building/installing the sampling drivers for your target system:
  • Windows* targets: Verify the sampling driver is installed correctly. If required, install the driver.
  • Linux* targets:
    • Make sure the driver is installed.
      • Build the driver, if required.
      • Install the driver, if required.
    • Verify the driver configuration.
  • Android* targets: Verify the sampling driver is installed. If required, build and install the driver.
  • You may need kernel header sources and other additional software to build and load the kernel drivers on Linux. For details, see the
    README.txt
     file in the
    sepdk/src
     directory.
  • A Linux kernel update can lead to incompatibility with
    VTune
    Profiler
     drivers set up on the system for event-based sampling (EBS) analysis. If the system has installed
    VTune
    Profiler
     boot scripts to load the drivers into the kernel each time the system is rebooted, the drivers will be automatically re-built by the boot scripts at system boot time. Kernel development sources required for driver rebuild should correspond to the Linux kernel update.
  • If you loaded the drivers but do not use them and no collection is happening, there is no execution time overhead of having the drivers loaded. The memory overhead is also minimal. You can let the drivers be loaded at boot time (for example, via the
    install-boot-script
    , which is used by default) and not worry about it. Unless data is being collected by the
    VTune
    Profiler
    , there will be no latency impact on system performance.

Product and Performance Information

1

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