Intel® VTune™ Amplifier 201

Disk Input and Output Analysis

Use a platform-wide Disk Input and Output analysis to monitor utilization of the disk subsystem, CPU and processor buses.

Note

This is a PREVIEW FEATURE on Windows* OS. A preview feature may or may not appear in a future production release. It is available for your use in the hopes that you will provide feedback on its usefulness and help determine its future. Data collected with a preview feature is not guaranteed to be backward compatible with future releases. Please send your feedback to parallel.studio.support@intel.com or to intelsystemstudio@intel.com.

This analysis type uses the hardware event-based sampling collection and system-wide Ftrace* collection (for Linux* and Android* targets)/ETW collection (Windows* targets) to provide a consistent view of the storage sub-system combined with hardware events and an easy-to-use method to match user-level source code with I/O packets executed by the hardware.

Disk Input and Output Analysis

The analysis actively relies on the data produced by the kernel block driver system. In case your platform utilizes a non-standard block driver sub-system (for example, user-space storage drivers), disk metrics will not be available in the analysis type.

The Disk Input and Output analysis helps identify:

To run the Disk Input/Output analysis, explore:

I/O Analysis Metrics

VTune Amplifier uses the following system-wide metrics for the Disk I/O analysis:

Configuration Options

Prerequisites:

To run the Disk Input and Output analysis:

  1. Click the (standalone GUI)/ (Visual Studio IDE)New Analysis button on the Intel® VTune™ Amplifier toolbar.

    The New Amplifier Result tab opens with the Analysis Type window active.

  2. From the analysis tree on the left pane, select Platform Analysis > Disk Input and Output.

    The analysis configuration pane opens on the right.

    This predefined analysis type does not provide additional options (knobs) to configure.

  3. Click Start to run the analysis.

To run the Disk Input/Output analysis from the command line, enter:

$ amplxe-cl -collect disk-io -- <target> [target_options]

Viewpoints

VTune Amplifier collects the data, generates a rxxxdiskio result, and opens it in the default Disk Input and Output viewpoint that displays statistics on I/O waits (Linux targets only), I/O operations and I/O data transfers distributed over time and correlated with the data on the application execution. Start with the Disk Input and Output Histogram sections of the Summary window. Identify slow I/O operations and switch to the grid view for further analysis.

What's Next

If you identified imbalance between I/O and compute operations, consider modifying your code to make I/O operations asynchronous.

For I/O requests with long latency, check whether your data can be pre-loaded, written incrementally, or consider upgrading your storage device (to SSD, for example).

See Also