Intel® VTune™ Profiler

User Guide

ID 766319
Date 12/20/2024
Public
Document Table of Contents

Sampling Drivers

Intel® VTune™ Profiler uses kernel drivers to enable hardware event-based sampling. During installation, the VTune Profiler installer uses the Sampling Driver Kit to build drivers for your kernel with the default installation options.

Sometimes, the sampling drivers may not get built and set up during installation, possibly due to lack of privileges or missing kernel development RPM. In the installation process, you see an error message about this issue. On Linux* host and Android* (collector package only) systems, VTune Profiler enables driverless sampling data collection which uses the Linux Perf* tool functionality. Driverless collection may have some analysis limitations for a non-root user. VTune Profiler also uses the driverless mode on Linux systems when hardware event-based sampling collection is run with stack analysis as in Hotspots or Threading analysis types.

To enable a driver-based sampling data collection, follow these procedures to verify or install sampling drivers for:

Aspects of Using Sampling Drivers

  • To build and load the kernel drivers on Linux systems, you may need kernel header sources and additional software. For more information, see the README.txt file in the sepdk/src directory.

  • A Linux kernel update can cause compatibility issues with the sampling drivers set up on your system for event-based sampling (EBS) analysis. If your system has installed VTune Profiler boot scripts to load the drivers into the kernel each time the system is rebooted, at system boot time, the drivers are rebuilt by the boot scripts. The kernel development sources necessary to rebuild the drivers should correspond to the Linux kernel update.

  • If you load the drivers but do not use them and no collection is happening, there is no execution time overhead caused by loading the drivers. The memory overhead is also minimal. Allowing drivers be loaded at boot time (for example, through the install-boot-script, which is used by default) does not create overhead. Unless VTune Profiler collects data, the use of sampling drivers has no latency impact on system performance.