《嵌入式软件的时间分析》从书中到实践-使用Tracealyzer进行RTOS堆分析
<div class='showpostmsg'><p>书中分享了很多理论，方法和案例，</p><p>基于本书，本人在此基础上再分享一些更贴近实战的案例分享。</p>
<p>本人公众号 嵌入式Lee（嵌入式软硬件技术:RTOS,GUI,FS,协议栈,ARM,总线,嵌入式C,开发环境 and blablaba....多年经验分享,非硬货不发,带你扒开每一个技术背后的根本原理。）</p>
<p> </p>
<div></div>
<h1>一. <strong>前言</strong></h1>
<p>前面分享了使用Tracealyzer进行RTOS任务栈分析，这一篇继续分享另外一个很重要的实践案例即堆的使用分析。</p>
<h1>二. <strong>事件</strong></h1>
<p>启动时xTraceKernelPortEnable创建事件记录PSF_EVENT_HEAP_CREATE</p>
<section>
<pre>
<code>if (pxKernelPortData->xSystemHeapHandle == 0)
{
xTraceHeapCreate("System Heap", 0, 0, configTOTAL_HEAP_SIZE, &pxKernelPortData->xSystemHeapHandle);
}</code></pre>
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</section>
<p>FreeRTOSConfig.h需要配置堆大小我这里使用了编译器符号，&_heap_size，按照实际设置即可。</p>
<pre>
<code>#define configTOTAL_HEAP_SIZE &_heap_size</code></pre>
<p>xTraceHeapCreate实现如下，会发送事件PSF_EVENT_HEAP_CREATE</p>
<section>
<pre>
<code>traceResult xTraceHeapCreate(const char *szName, TraceUnsignedBaseType_t uxCurrent, TraceUnsignedBaseType_t uxHighWaterMark, TraceUnsignedBaseType_t uxMax, TraceHeapHandle_t *pxHeapHandle)
{
TraceUnsignedBaseType_t uxStates;
uxStates = uxCurrent;
uxStates = uxHighWaterMark;
uxStates = uxMax;
return xTraceObjectRegisterInternal(PSF_EVENT_HEAP_CREATE, 0, szName, 3, uxStates, TRC_ENTRY_OPTION_HEAP, (TraceObjectHandle_t*)pxHeapHandle);
}</code></pre>
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</section>
<p>事件记录如下，即一个指针加3个WORD的uxStates信息</p>
<section>
<pre>
<code>if (xTraceEventBegin(uiEventCode, sizeof(void*) + uxStateCount * sizeof(TraceUnsignedBaseType_t), &xEventHandle) == TRC_SUCCESS)
{
xTraceEventAddPointer(xEventHandle, pvObject);
for (i = 0; i < uxStateCount; i++)
{
xTraceEventAddUnsignedBaseType(xEventHandle, uxStates);
}
xTraceEventEnd(xEventHandle);
}</code></pre>
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</section>
<p> </p>
<p>宏TRC_CFG_INCLUDE_MEMMANG_EVENTS要配置为1</p>
<p>TRC_CFG_SCHEDULING_ONLY配置为0</p>
<p>在pvPortMalloc和pvPortFree接口中，对应的事件记录处理</p>
<p>trcKernelPort.h中</p>
<section>
<pre>
<code>#undef traceMALLOC
#define traceMALLOC( pvAddress, uiSize ) \
if (xTraceIsRecorderEnabled()) \
{ \
xTraceHeapAlloc(xTraceKernelPortGetSystemHeapHandle(), pvAddress, uiSize); \
}
#undef traceFREE
#define traceFREE( pvAddress, uiSize ) \
if (xTraceIsRecorderEnabled()) \
{ \
xTraceHeapFree(xTraceKernelPortGetSystemHeapHandle(), pvAddress, uiSize); \
}
#endif
</code></pre>
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</section>
<p> </p>
<p>最终调用xTraceHeapAlloc和xTraceHeapFree实现</p>
<p>存储的事件为</p>
<p>PSF_EVENT_MALLOC 或PSF_EVENT_MALLOC_FAILED，参数是一个地址一个大小</p>
<section>
<pre>
<code> if (xTraceEventBegin(pvAddress != 0 ? PSF_EVENT_MALLOC : PSF_EVENT_MALLOC_FAILED, sizeof(void*) + sizeof(TraceUnsignedBaseType_t), &xEventHandle) == TRC_SUCCESS)
{
xTraceEventAddPointer(xEventHandle, pvAddress);
xTraceEventAddUnsignedBaseType(xEventHandle, uxSize);
xTraceEventEnd(xEventHandle);
}</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p>PSF_EVENT_FREE 或PSF_EVENT_FREE_FAILED，参数是一个地址一个大小</p>
<section>
<pre>
<code> if (xTraceEventBegin(pvAddress != 0 ? PSF_EVENT_FREE : PSF_EVENT_FREE_FAILED, sizeof(void*) + sizeof(TraceUnsignedBaseType_t), &xEventHandle) == TRC_SUCCESS)
{
xTraceEventAddPointer(xEventHandle, pvAddress);
xTraceEventAddUnsignedBaseType(xEventHandle, uxSize);
xTraceEventEnd(xEventHandle);
}</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p>事件信息存储在</p>
<p>全局变量pxKernelPortData->xSystemHeapHandle中</p>
<p>对应的初始化</p>
<section>
<pre>
<code>traceResult xTraceHeapCreate(const char *szName, TraceUnsignedBaseType_t uxCurrent, TraceUnsignedBaseType_t uxHighWaterMark, TraceUnsignedBaseType_t uxMax, TraceHeapHandle_t *pxHeapHandle)
{
TraceUnsignedBaseType_t uxStates;
uxStates = uxCurrent;
uxStates = uxHighWaterMark;
uxStates = uxMax;
return xTraceObjectRegisterInternal(PSF_EVENT_HEAP_CREATE, 0, szName, 3, uxStates, TRC_ENTRY_OPTION_HEAP, (TraceObjectHandle_t*)pxHeapHandle);
}</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p>xTraceHeapCreate调用xTraceObjectRegisterInternal，从&pxEntryTable->axEntries中创建分配空间出来</p>
<pre>
<code> *pxObjectHandle = (TraceObjectHandle_t)xEntryHandle;</code></pre>
<p>所以pxKernelPortData->xSystemHeapHandle即指向上述pxEntryTable->axEntries分配出来的xEntryHandle，</p>
<p>指向的内容是</p>
<p>如下3个索引的WORD,即当前值，heap的最大值，heap的最大使用值。</p>
<section>
<pre>
<code>#define TRC_HEAP_STATE_INDEX_CURRENT 0
#define TRC_HEAP_STATE_INDEX_HIGHWATERMARK1
#define TRC_HEAP_STATE_INDEX_MAX 2</code></pre>
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</section>
<p> </p>
<p>以下就是获取出CURRENT值</p>
<section>
<pre>
<code> if (pvAddress != 0)
{
/* This should never fail */
TRC_ASSERT_ALWAYS_EVALUATE(xTraceEntryGetState(xHeapHandle, TRC_HEAP_STATE_INDEX_CURRENT, &uxCurrent) == TRC_SUCCESS);
/* This should never fail */
TRC_ASSERT_ALWAYS_EVALUATE(xTraceEntryGetState(xHeapHandle, TRC_HEAP_STATE_INDEX_HIGHWATERMARK, &uxHighWaterMark) == TRC_SUCCESS);
uxCurrent += uxSize;
if (uxCurrent > uxHighWaterMark)
{
uxHighWaterMark = uxCurrent;
/* This should never fail */
TRC_ASSERT_ALWAYS_EVALUATE(xTraceEntrySetState(xHeapHandle, TRC_HEAP_STATE_INDEX_HIGHWATERMARK, uxHighWaterMark) == TRC_SUCCESS);
}
/* This should never fail */
TRC_ASSERT_ALWAYS_EVALUATE(xTraceEntrySetState(xHeapHandle, TRC_HEAP_STATE_INDEX_CURRENT, uxCurrent) == TRC_SUCCESS);
}
</code></pre>
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</section>
<p>抓包事件如下，2个参数</p>
<section>
<pre>
<code>#define PSF_EVENT_MALLOC 0x38
#define PSF_EVENT_FREE 0x39
#define PSF_EVENT_MALLOC_FAILED 0xE9
#define PSF_EVENT_FREE_FAILED 0xEA
</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p> </p>
<p>那么找如下字段即可</p>
<p>0x38 0x20</p>
<p>0x39 0x20</p>
<p>0xE9 0x20</p>
<p>0xEA 0x20</p>
<p>必然要如下38 20表示MALLOC事件，0x009C是事件计数，</p>
<p>0x00007EAC是时间戳，0x081096E0是堆地址，0x00000070是申请的大小112字节。</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p> </p>
<h1>三. <strong>实测</strong></h1>
<p>菜单栏views->Memory Heap Utilization打开窗口</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p>显示堆的申请和释放过程，实际就是一个计数器，申请就递增，释放就减少，如果这个数一</p>
<p>直递增说明申请的多释放的少，最终导致堆不够。</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p>Event log视图也可以看到事件</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p>Trace视图也可以看到事件</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p>Trace视图双击malloc或者free，弹出窗口，显示malloc和free的历史，可以看到谁申请了什么时候释放了，这样可以追踪申请和释放是否正常</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p> </p>
<h1>四. <strong>总结</strong></h1>
<p>以上分享使用Tracealyzer进行堆分析的案例，实际就是一个计数器事件，malloc则计数值增加free则递减，可以看到什么时候malloc什么时候free，如果有未free则可以通过图表结合前后事件分析出来。</p>
<p> </p>
<p> </p>
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