User Guide

Contents

Linux* and Android* Kernel Analysis

Use an event library provided in the Custom Analysis configuration to select Linux* Ftrace* and Android* framework events to monitor with the event-based sampling collector.
To choose events from the library:
  1. The new analysis type shows up under
    Custom Analysis
    in the
    HOW
    pane of the
    Configure Analysis
    window.
  2. In the new custom configuration, use the
    Linux Ftrace events
    or
    Android framework events
    area to specify events for monitoring a system behavior:
    For example, for KVM guest OS profiling consider selecting the following Linux Ftrace events to track IRQ injection process: kvm, irq, sofirq and workq.
The collected data shows up as tasks in the default viewpoint. Start with the
Summary
window to identify the most time-consuming tasks in the
Top Tasks
section. Analyze task duration statistics presented by task type in the
Task Duration
histogram:
Use the sliders to set up thresholds for high and slow task instances.
Clicking a task in the
Top Tasks
section opens the
Bottom-up
window grouped by tasks. To analyze tasks over time, switch to the
Platform
window:
VTune 
         Profiler Platform Window

Limitations

On some systems, the Linux Ftrace subsystem, located in the debugfs partition in
/sys/kernel/debug/tracing
, may be accessible for the root user only. In this case, the
VTune
Profiler
provides an error message:
Ftrace collection is not possible due to a lack of credentials. Root privileges are required
. To enable Ftrace events collection on such a system, you may either run the
VTune
Profiler
with root privileges or change permissions manually by using the
chown
command under the root account, for example:
$ chown -R <
user
>:<
group
> /sys/kernel/debug/tracing
You can automate this process by using the
prepare_debugfs.sh
script located in the
bin
directory. The script mounts debugfs, changes permissions to a desired group, and updates the install boot script to apply this change automatically on the system startup. To execute this script, make sure to use root privileges.
To change permissions automatically with the
prepare_debugfs.sh
script, enter:
$ ./install/bin64/prepare-debugfs.sh [
option
]
where
[
option
]
is one of the following:
Option
Description
-h | --help
Display usage information.
-i | --install
Configure the without options, script will configure debugfs boot script and install it in the appropriate system directory.
-c | --check
Mount without options, script will configure debugfs and check permissions.
-u | --uninstall
Uninstall a previously installed debugfs boot script and revert configuration.
-g | --group <group>
Specify group other than
vtune
.
-r | --revert
Revert debugfs configuration.
-b | --batch
Run in a non-interactive mode (exiting in case of already changed permissions) without options. The script will configure debugfs.

Product and Performance Information

1

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804