User Guide

  • 2020
  • 06/18/2020
  • Public Content
Contents

System Overview Analysis

Use a platform-wide System Overview analysis to monitor a general behavior of your target system and identify platform-level factors that limit performance.
The System Overview analysis supports the following profiling modes:
  • Hardware Event-Based Sampling serves as an entry-point analysis to identify how effectively your code utilizes CPU, GPU, DRAM, I/O, and PCIe.
  • Hardware Tracing (Linux* and Android* targets) analyzes your code at the microsecond level and helps identify a cause of latency issues.

Hardware Event-Based Sampling Mode

In this mode, you can capture overall CPU, GPU, and I/O resources utilization and see recommendations for next steps. Use this mode as an entry-level analysis to triage system performance issues.
System Overview Analysis
For Linux targets, the System Overview analysis collects the following Ftrace* events: sched, freq, idle, workq, irq, softirq.
For Android targets, the System Overview analysis collects the following events:
  • Atrace* events: input, view, webview, audio, video, camera, hal, res, dalvik
  • Ftrace events: sched, freq, idle, workq, filesystem, irq, softirq, sync, disk

Hardware Tracing Mode (Linux and Android Targets)

Use this mode to capture CPU core activities at the microsecond level and detect unusual behavior.
Prerequisites:
  • To enable system-level analysis for this mode, consider setting the
    /proc/sys/kernel/perf_event_paranoid
    value to 0 or less.
  • To see the kernel module and its symbols, set
    /proc/sys/kernel/kptr_restrict
    to 0.
  • Make sure there is a disk space on both target and host systems. Depending on the number of CPU cores, the amount of collected data may reach 1GB per second.
  • Make sure your kernel version is 4.3 or higher.
In the hardware tracing mode, you can do the following:
  • Analyze user/kernel mode transitions and interrupts
  • Explore execution of unexpected processes or system services
  • Measure particular stages of workload execution without static instrumentation
  • Analyze CPU core activities at the microsecond level
  • Analyze a kernel/driver or application module by measuring exact CPU time with a nanosecond precision
  • Triage latency issues resulted from:
    • changes in the execution code flow
    • preemption by another process
    • resource sharing issues
    • page faults
    • power consumption issues caused by unexpected wake-ups
  • This analysis requires a direct access to the hardware. It does not work inside a Guest VM.
  • In most cases, the collection overhead in this mode is less than 10%. It can be higher if your application is IO or DRAM bound.
  • The Hardware Tracing mode does not require sampling drivers.

Configure and Run Analysis

To configure options for the System Overview analysis:
Prerequisites
: Create a project .
  1. Click the
    Configure Analysis
    button on
    Intel® VTune™
    Profiler
    toolbar.
    The
    Configure Analysis
    window opens.
  2. From
    HOW
    pane, click the Browse button and select
    System Overview
    .
  3. Select
    Hardware Tracing
    or
    Hardware Event-Based Sampling
    mode.
    For the
    Hardware Tracing
    mode, you can also enable the
    Analyze interrupts
    option.
    With the default
    Hardware Tracing
    configuration,
    Intel® VTune™
    Profiler
    stops the data collection when a 1GB data limit is reached. You can change this limit in the
    Advanced
    section of the
    WHAT
    pane:
  4. Click the Start button to run the analysis.
VTune
Profiler
collects the data, generates a
rxxxso
result, and opens it in the default System Overview viewpoint.
You may generate the command line for this configuration using the Command Line button at the bottom.

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