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   <section id="run-time-stack-statistics">
 <h1>Run time stack statistics<a class="headerlink" href="#run-time-stack-statistics" title="Permalink to this heading"></a></h1>
 <section id="introduce">
 <h2>Introduce<a class="headerlink" href="#introduce" title="Permalink to this heading"></a></h2>
 <p>When debugging code, it is often necessary to focus on how to track
 the maximum stack usage of the calling functions in order to optimize
 the code structure and reduce stack usage. This article will introduce
 a method based on the running state to track the deepest call stack of all tasks.</p>
 </section>
 <section id="configuration">
 <h2>Configuration<a class="headerlink" href="#configuration" title="Permalink to this heading"></a></h2>
 <blockquote>
 <div><div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">CONFIG_SCHED_STACKRECORD</span><span class="o">=</span><span class="mi">32</span>
 <span class="n">CONFIG_ARCH_INSTRUMENT_ALL</span><span class="o">=</span><span class="n">y</span>
 </pre></div>
 </div>
 </div></blockquote>
 <p><code class="docutils literal notranslate"><span class="pre">`CONFIG_SCHED_STACKRECORD`</span></code> is used to record the maximum stack usage of all tasks
 <code class="docutils literal notranslate"><span class="pre">`CONFIG_ARCH_INSTRUMENT_ALL`</span></code> is used to instrument all code.</p>
 <p>Please note that CONFIG_ARCH_INSTRUMENT_ALL is not necessary.
 This configuration option will instrument all code,
 but if you only want to instrument specific functions,
 you can add ‘-finstrument-functions’ to the corresponding makefile.</p>
 </section>
 <section id="example">
 <h2>Example<a class="headerlink" href="#example" title="Permalink to this heading"></a></h2>
 <ol class="arabic">
 <li><p><code class="docutils literal notranslate"><span class="pre">`./tools/configure.sh</span> <span class="pre">esp32c3-devkit:stack`</span></code></p></li>
 <li><p><code class="docutils literal notranslate"><span class="pre">`make</span> <span class="pre">-j20`</span></code></p></li>
 <li><p>flash the image to your board
 .. code-block :: bash</p>
 <blockquote>
 <div><p>nsh&gt; cat /proc/1/stack
 StackAlloc: 0x3fc8b5b0
 StackBase:  0x3fc8b5e0
 StackSize:  2000
 MaxStackUsed:1344
 Backtrace         Size
 0x42009198          32
 0x42009200          48
 0x420081a0         128
 0x42008d18          64
 0x4201da60          80
 0x420199e0          80
 0x42018c6c          48
 0x420194f4          48
 0x42017d30          32
 0x4201634c          32
 0x420163ac          48
 0x42016408          32
 0x420132c0          48
 0x42010598          32
 0x4200fd98          48
 0x4200f5dc          80
 0x4200f8e0         160</p>
 </div></blockquote>
 </li>
 </ol>
 </section>
 <section id="implementation-details">
 <h2>Implementation details<a class="headerlink" href="#implementation-details" title="Permalink to this heading"></a></h2>
 <p>The specific principle is based on the instrumentation of gcc.
 In the TCB (Thread Control Block) of the corresponding task,
 the maximum value of the stack pointer (sp) is recorded at the entry of each function.
 If it is the maximum value, the backtrace is recorded.</p>
 </section>
 <section id="notice">
 <h2>Notice<a class="headerlink" href="#notice" title="Permalink to this heading"></a></h2>
 <p>Be cautious when using the CONFIG_ARCH_INSTRUMENT_ALL option:
 1. It will instrument every function, which may have a risk of recursion.
 2. It will also instrument entry functions, such as _start(). At this point,
 the bss segment and data segment have not been initialized,
 which may cause errors. The current implementation uses a magic number to avoid this,
 but it performs poorly during hot start. The solution is to mark
 the entry function with the noinstrument_function flag to prevent instrumentation.</p>
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	<section id="run-time-stack-statistics">
	<h1>Run time stack statistics<a class="headerlink" href="#run-time-stack-statistics" title="Permalink to this heading"></a></h1>
	<section id="introduce">
	<h2>Introduce<a class="headerlink" href="#introduce" title="Permalink to this heading"></a></h2>
	<p>When debugging code, it is often necessary to focus on how to track
	the maximum stack usage of the calling functions in order to optimize
	the code structure and reduce stack usage. This article will introduce
	a method based on the running state to track the deepest call stack of all tasks.</p>
	</section>
	<section id="configuration">
	<h2>Configuration<a class="headerlink" href="#configuration" title="Permalink to this heading"></a></h2>
	<blockquote>
	<div><div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="n">CONFIG_SCHED_STACKRECORD</span><span class="o">=</span><span class="mi">32</span>
	<span class="n">CONFIG_ARCH_INSTRUMENT_ALL</span><span class="o">=</span><span class="n">y</span>
	</pre></div>
	</div>
	</div></blockquote>
	<p><code class="docutils literal notranslate"><span class="pre">`CONFIG_SCHED_STACKRECORD`</span></code> is used to record the maximum stack usage of all tasks
	<code class="docutils literal notranslate"><span class="pre">`CONFIG_ARCH_INSTRUMENT_ALL`</span></code> is used to instrument all code.</p>
	<p>Please note that CONFIG_ARCH_INSTRUMENT_ALL is not necessary.
	This configuration option will instrument all code,
	but if you only want to instrument specific functions,
	you can add ‘-finstrument-functions’ to the corresponding makefile.</p>
	</section>
	<section id="example">
	<h2>Example<a class="headerlink" href="#example" title="Permalink to this heading"></a></h2>
	<ol class="arabic">
	<li><p><code class="docutils literal notranslate"><span class="pre">`./tools/configure.sh</span> <span class="pre">esp32c3-devkit:stack`</span></code></p></li>
	<li><p><code class="docutils literal notranslate"><span class="pre">`make</span> <span class="pre">-j20`</span></code></p></li>
	<li><p>flash the image to your board
	.. code-block :: bash</p>
	<blockquote>
	<div><p>nsh> cat /proc/1/stack
	StackAlloc: 0x3fc8b5b0
	StackBase: 0x3fc8b5e0
	StackSize: 2000
	MaxStackUsed:1344
	Backtrace Size
	0x42009198 32
	0x42009200 48
	0x420081a0 128
	0x42008d18 64
	0x4201da60 80
	0x420199e0 80
	0x42018c6c 48
	0x420194f4 48
	0x42017d30 32
	0x4201634c 32
	0x420163ac 48
	0x42016408 32
	0x420132c0 48
	0x42010598 32
	0x4200fd98 48
	0x4200f5dc 80
	0x4200f8e0 160</p>
	</div></blockquote>
	</li>
	</ol>
	</section>
	<section id="implementation-details">
	<h2>Implementation details<a class="headerlink" href="#implementation-details" title="Permalink to this heading"></a></h2>
	<p>The specific principle is based on the instrumentation of gcc.
	In the TCB (Thread Control Block) of the corresponding task,
	the maximum value of the stack pointer (sp) is recorded at the entry of each function.
	If it is the maximum value, the backtrace is recorded.</p>
	</section>
	<section id="notice">
	<h2>Notice<a class="headerlink" href="#notice" title="Permalink to this heading"></a></h2>
	<p>Be cautious when using the CONFIG_ARCH_INSTRUMENT_ALL option:
	1. It will instrument every function, which may have a risk of recursion.
	2. It will also instrument entry functions, such as _start(). At this point,
	the bss segment and data segment have not been initialized,
	which may cause errors. The current implementation uses a magic number to avoid this,
	but it performs poorly during hot start. The solution is to mark
	the entry function with the noinstrument_function flag to prevent instrumentation.</p>
	</section>
	</section>


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