docs/html/tools/performance/hierarchy-viewer/profiling.jd

page.title=Profiling with Hierarchy Viewer
meta.tags="android, performance, profiling, tools, rendering, hierarchyviewer
page.tags="android", "performance", "profiling", "tools", "rendering", "hierarchyviewer"
page.metaDescription=Profile the relative rendering speed for each view.
page.image=tools/performance/thumbnails/tools_hierarchy_viewer_profiling.png
page.article=true

@jd:body

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<h2>In this document</h2>
<ul>
  <li><a href="#WhatYouNeed">Prerequisites</a></li>
  <li><a href="#ProfilingWithHierarchyViewer">Profiling with Hierarchy Viewer</a></li>
  <li><a href="#InterpretingResults">Interpreting Profiling Results</a></li>

</ul>
</div>

<p>This walkthrough shows you how to profile your app's view hiearchy with
  Hierarchy Viewer, and how to interpret the results.</p>

<h2 id="WhatYouNeed">Prerequisites</h2>

<ul>
  <li><a href="{@docRoot}tools/performance/hierarchy-viewer/setup.html">
    Device Setup for Hierarchy Viewer</a></li>
  <li><a href="{@docRoot}tools/performance/hierarchy-viewer/index.html">
    Hierarchy Viewer Walkthrough</a></li>
</ul>

<h2 id="ProfilingWithHierarchyViewer">Profiling Steps</h2>

<ul class="no-bullet">
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 <li><div style="overflow:hidden">

  <ol class="padded">

  <div class="figure" style="">
<img src="{@docRoot}images/tools/performance/hierarchy-viewer/gettingstarted_image014.png"
         alt=""
         width="400px" />
      <p class="img-caption">
        <strong>Figure 1. </strong>View hierarchy after profiling.
      </p>
    </div>

    <li>Start Hierarchy Viewer for your app.</li>

    <li>In the <b>Tree View</b> or the <b>Layout View</b>, click on the View node whose
      children you want to profile.</li>

    <li>To start profiling, click the small button with three circles
<img src="{@docRoot}images/tools/performance/hierarchy-viewer/gettingstarted_image013.png">
      at the top of the Tree View.

    </li>

    <li>For large view hierarchies, profiling may take a few seconds.</li>

    <li>Each view in your subtree gets three dots, which can be green, yellow, or red.

      <ul>
        <li>The left dot represents the Draw Process of the rendering pipeline.</li>
        <li>The middle dot represents the Layout Phase.</li>
        <li>The right dot represents the Execute Phase.</li>
      </ul>
    </li>

</ol></div>

</li>

<li><div style="overflow:hidden">
<hr>
  <ol class="padded" start="5">

    <div class="figure" style="">
<img src="{@docRoot}images/tools/performance/hierarchy-viewer/gettingstarted_image015.png"
         alt=""
         width="240px" />
      <p class="img-caption">
        <strong>Figure 2. </strong>How the colored dots relate<br>to the rendering pipeline.
      </p>
    </div>

    <li>These dots roughly correspond to the Measure,
     Layout, and Draw
      phases of the processing pipeline.</li>

    <li>The color of the dots indicates the relative performance
      of this node in respect to all other profiled nodes.

      <ul>
        <li><strong>Green</strong> means the view renders faster than at least
          half of the other views.</li>

        <li><strong>Yellow</strong> means the view renders faster than the bottom
          half of the other views.</li>

        <li><strong>Red</strong> means the view is among the slowest
         half of views.</li>
      </ul>
    </li>

    </ol>
</div></li>
</ul>

  <h2 id="InterpretingResults">Interpreting Hierarchy Viewer Profiling Results</h2>

    <p>Hierarchy Viewer measures the <em>relative performance</em> of a
      node</b>, so there are always red nodes in a profile, and it
      doesn't necessarily mean that view is too slow for the users of
      your app.</p>

    <p>Hierarchy Viewer software rasterizes your Activity to acquire the timing
      information. Rasterization is the process of taking a high-level primitive, such as a
      circle or a vector font, and turning it into pixels on the screen. Typically,
      rasterization is done by the GPU on your device, but in the case of
      software rasterization, rendering is done on the CPU with
      ordinary software. This means that the absolute
      reported timings are correct relative to each other, but are bloated and vary
      depending on the overall and changing CPU workload on your device and PC. Profile
      several times to get a feel for the average measurements.</p>

    <p>The following are guidelines for interpreting Hierarchy Viewer profiling output.</p>

    <p>A red node is a potential problem in any situation where your app has
      unexpectedly slow performance. In a relative setting, there is always a
      slowest node; make sure it is the node you expect.
      The following examples illustrate how to interpret red dots.</p>

      <ul>
        <li>Look for red dots in leaf nodes or view groups with only a few children. This
          might point to a problem. Your app may not be slow, or it may not be slow on your
          device, but you need to be aware of why that dot is red.
          <a href="{@docRoot}tools/performance/systrace/index.html"> Systrace</a> or
          <a href="{@docRoot}tools/performance/traceview/index.html"> Traceview</a>
          can give you additional information. </li>

        <li>If you have a view group with many children and a red measure phase, take a
          look at the children to see how they are performing.</li>

        <li>A view with yellow or even red dots might not be performing slowly on the
          device. That's where the actual numbers are helpful.
          <a href="{@docRoot}tools/performance/systrace/index.html"> Systrace</a> or
          <a href="{@docRoot}tools/performance/traceview/index.html"> Traceview</a>
          can give you additional information.</li>

        <li>If the root view of a hierarchy has a red measure phase, red layout phase, and
          yellow draw phase, this is somewhat typical, because it's the
          parent of all the other views.</li>

        <li>If a leaf node in a tree with 20+ views has a red draw phase, this <i>is</i> a
          problem. Check your OnDraw method for code that shouldn't be
          there.</li>
       </ul>