《嵌入式软件的时间分析》从书中到实践-Tracealyzer事件记录格式与丢事件监测
<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>本文继续在前面的基础上分析Tracealyzer发送到上位机的事件信息是如何记录的。</p>
<p>直接从代码结合抓包数据进行分析。</p>
<h1><strong>二.事件记录格式</strong></h1>
<p>trcKernelPort.h中定义了很多事件类型,以PSF_EVENT_开头</p>
<p> </p>
<div style="text-align: center;"></div>
<p> </p>
<p>每次记录事件，都是按照如下形式进行</p>
<p>先xTraceEventBegin</p>
<p>然后TraceEventAddxxx</p>
<p>然后xTraceEventEnd</p>
<p>其中xTraceEventBegin调用xTraceEventBeginOffline即宏TRC_EVENT_BEGIN_OFFLINE实现如下</p>
<section>
<pre>
<code>#define TRC_EVENT_BEGIN_OFFLINE(uiEventCode, uiPayloadSize, pxEventHandle) \
( \
(xTraceEventBeginRawOffline(sizeof(TraceBaseEvent_t) + (uiPayloadSize), pxEventHandle)) == TRC_SUCCESS ? \
( \
pxTraceEventDataTable->coreEventData.eventCounter++, \
SET_BASE_EVENT_DATA((TraceBaseEvent_t*)(((TraceEventData_t*)*(pxEventHandle))->pvBlob), \
uiEventCode, \
(((TraceEventData_t*)*(pxEventHandle))->size - sizeof(TraceBaseEvent_t)) / sizeof(uint32_t), \
pxTraceEventDataTable->coreEventData.eventCounter), \
((TraceEventData_t*)*(pxEventHandle))->offset += sizeof(TraceBaseEvent_t), \
TRC_SUCCESS \
) : TRC_FAIL \
)</code></pre>
<pre data-lang="properties">
<span style="white-space: normal">其中eventCounter++即递增事件计数，SET_BASE_EVENT_DATA即设置每个事件的基本信息，</span></pre>
</section>
<p>事件格式,即如下包括事件ID，总的事件计数，和时间戳</p>
<p> </p>
<pre>
<code>/**
* @internal Trace Base Event Structure
*/
typedef struct {
uint16_t EventID; /**< */
uint16_t EventCount; /**< */
uint32_t TS; /**< */
} TraceBaseEvent_t;</code></pre>
<p>其中 SET_BASE_EVENT_DATA实现如下</p>
<section>
<pre>
<code>#define SET_BASE_EVENT_DATA(pxEvent, eventId, paramCount, eventCount) \
( \
(pxEvent)->EventID = TRC_EVENT_SET_PARAM_COUNT(eventId, paramCount), \
(pxEvent)->EventCount = TRC_EVENT_SET_EVENT_COUNT(eventCount), \
xTraceTimestampGet(&(pxEvent)->TS) \
)</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p> </p>
<p>事件ID，TRC_EVENT_SET_PARAM_COUNT如下高4位表示参数个数，低12位表示事件类型，即PSF_EVENT_开始的宏。</p>
<pre>
<code>#define TRC_EVENT_SET_PARAM_COUNT(id, n) (((uint16_t)(id)) | ((((uint16_t)(n)) & 0xF) << 12))</code></pre>
<p> </p>
<p>所以可以看到事件记录格式如下</p>
<p>EEWORLDIMGTK1</p>
<p> </p>
<p>添加了上述信息后然后调用TraceEventAddxxx添加参数，</p>
<p>最后调用xTraceEventEnd将事件写入到发送缓存中。</p>
<p>以任务切换事件为例，如果切换到执行某个任务，则回调traceTASK_SWITCHED_IN</p>
<p>即xTraceTaskSwitch</p>
<section>
<pre>
<code>traceResult xTraceTaskSwitch(void *pvTask, TraceUnsignedBaseType_t uxPriority)
{
traceResult xResult = TRC_FAIL;
TraceEventHandle_t xEventHandle = 0;
void* pvCurrent = 0;
TRACE_ALLOC_CRITICAL_SECTION();
(void)pvTask;
(void)uxPriority;
if (xTraceIsRecorderEnabled() == 0)
{
return xResult;
}
TRACE_ENTER_CRITICAL_SECTION();
xTraceStateSet(TRC_STATE_IN_TASKSWITCH);
xTraceTaskGetCurrent(&pvCurrent);
if (pvCurrent != pvTask)
{
xTraceTaskSetCurrent(pvTask);
if (xTraceEventBegin(PSF_EVENT_TASK_ACTIVATE, sizeof(void*) + sizeof(uint32_t), &xEventHandle) == TRC_SUCCESS)
{
xTraceEventAddPointer(xEventHandle, pvTask);
xTraceEventAdd32(xEventHandle, (uint32_t)uxPriority);
xTraceEventEnd(xEventHandle);
xResult = TRC_SUCCESS;
}
}
xTraceStateSet(TRC_STATE_IN_APPLICATION);
TRACE_EXIT_CRITICAL_SECTION();
return xResult;
}</code></pre>
<p> </p>
</section>
<p>其中核心的事件记录处理如下</p>
<section>
<pre>
<code> if (xTraceEventBegin(PSF_EVENT_TASK_ACTIVATE, sizeof(void*) + sizeof(uint32_t), &xEventHandle) == TRC_SUCCESS)
{
xTraceEventAddPointer(xEventHandle, pvTask);
xTraceEventAdd32(xEventHandle, (uint32_t)uxPriority);
xTraceEventEnd(xEventHandle);
xResult = TRC_SUCCESS;
}</code></pre>
<p> </p>
</section>
<p>事件类型是PSF_EVENT_TASK_ACTIVATE=0x37</p>
<p>参数为两个</p>
<p>一个(void*)类型的任务地址，即pvTask</p>
<p>一个uint32_t类型的任务优先级,即uxPriority</p>
<p>所以传入xTraceEventBegin的参数大小是sizeof(void*) + sizeof(uint32_t)即两个WORD。</p>
<p>xTraceEventAddPointer添加指针参数，实现如下</p>
<section>
<pre>
<code>#define TRC_EVENT_ADD_POINTER(xEventHandle, value) \
TRC_COMMA_EXPR_TO_STATEMENT_EXPR_3( \
((void**)((TraceEventData_t*)(xEventHandle))->pvBlob)[((TraceEventData_t*)(xEventHandle))->offset / sizeof(void*)] = (value), \
((TraceEventData_t*)(xEventHandle))->offset += sizeof(void*), \
TRC_SUCCESS \
)</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p>xTraceEventAdd32添加ige无符号32位值，实现如下</p>
<section>
<pre>
<code>#define TRC_EVENT_ADD_32(xEventHandle, value) \
TRC_COMMA_EXPR_TO_STATEMENT_EXPR_3( \
((uint32_t*)((TraceEventData_t*)(xEventHandle))->pvBlob)[((TraceEventData_t*)(xEventHandle))->offset / sizeof(uint32_t)] = (value), \
((TraceEventData_t*)(xEventHandle))->offset += sizeof(uint32_t), \
TRC_SUCCESS \
)</code></pre>
<p> </p>
</section>
<p>xTraceEventAdd32添加ige无符号32位值，实现如下</p>
<section>
<pre>
<code>#define TRC_EVENT_ADD_32(xEventHandle, value) \
TRC_COMMA_EXPR_TO_STATEMENT_EXPR_3( \
((uint32_t*)((TraceEventData_t*)(xEventHandle))->pvBlob)[((TraceEventData_t*)(xEventHandle))->offset / sizeof(uint32_t)] = (value), \
((TraceEventData_t*)(xEventHandle))->offset += sizeof(uint32_t), \
TRC_SUCCESS \
)</code></pre>
<p> </p>
</section>
<p>上述基本事件信息和参数都存储在pvBlob开始的区域，</p>
<p>最后xTraceEventEnd->xTraceEventEndOffline->xTraceStreamPortCommit将事件存入发送缓存区。</p>
<p>最后清除pvBlob记录，以便下次继续进行事件记录。</p>
<section>
<pre>
<code>#define RESET_EVENT_DATA(p) \
( \
(p)->pvBlob = 0, \
(p)->size = 0, \
(p)->offset = 0 \
)</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p> </p>
<p>EEWORLDIMGTK2</p>
<p>对应抓取的包如下</p>
<p>0x2037表示是PSF_EVENT_TASK_ACTIVATE事件，0x00BE是事件计数值，0x00012809是时间戳，，0x081103A8是任务地址，0x00000001是任务优先级。</p>
<p>后面0x20EB是另外一个事件，事件参数有2个，事件ID是0xEB可以看到是PSF_EVENT_UNUSED_STACK，事件计数器0x00BF是在前一个事件基础上递增，时间戳是0x00013911，参数1是0x081103A8，参数2是0x00000FA0.</p>
<p>可以看到xTraceStackMonitorReport中，PSF_EVENT_UNUSED_STACK事件除了基本事件信息后面就是任务地址和栈最低MARK值，这里是0x00000FA0，说明该任务最少剩余该大小栈未使用。</p>
<section>
<pre>
<code> if (xTraceEventBegin(PSF_EVENT_UNUSED_STACK, sizeof(void*) + sizeof(uint32_t), &xEventHandle) == TRC_SUCCESS)
{
xTraceEventAddPointer(xEventHandle, pxStackMonitorEntry->pvTask);
xTraceEventAdd32(xEventHandle, (uint32_t)pxStackMonitorEntry->uxPreviousLowWaterMark);
xTraceEventEnd(xEventHandle);
}
</code></pre>
<div contenteditable="false" tabindex="-1"> </div>
</section>
<p> </p>
<p>EEWORLDIMGTK3</p>
<h1><strong>三.丢事件监测</strong></h1>
<p>EEWORLDIMGTK4</p>
<p>如上图live Stream可能会显示丢事件数，其实现原理如下</p>
<section>
<pre>
<code>#define TRC_EVENT_BEGIN_OFFLINE(uiEventCode, uiPayloadSize, pxEventHandle) \
( \
(xTraceEventBeginRawOffline(sizeof(TraceBaseEvent_t) + (uiPayloadSize), pxEventHandle)) == TRC_SUCCESS ? \
( \
pxTraceEventDataTable->coreEventData.eventCounter++, \
SET_BASE_EVENT_DATA((TraceBaseEvent_t*)(((TraceEventData_t*)*(pxEventHandle))->pvBlob), \
uiEventCode, \
(((TraceEventData_t*)*(pxEventHandle))->size - sizeof(TraceBaseEvent_t)) / sizeof(uint32_t), \
pxTraceEventDataTable->coreEventData.eventCounter), \
((TraceEventData_t*)*(pxEventHandle))->offset += sizeof(TraceBaseEvent_t), \
TRC_SUCCESS \
) : TRC_FAIL \
)</code></pre>
<p> </p>
</section>
<p>每记录一个事件时,TRC_EVENT_BEGIN_OFFLINE宏中,事件计数递增eventCounter++,然后</p>
<p>SET_BASE_EVENT_DATA记录到事件信息中</p>
<section>
<pre>
<code>typedef struct {
uint16_t EventID; /**< */
uint16_t EventCount; /**< */
uint32_t TS; /**< */
} TraceBaseEvent_t;</code></pre>
<p> </p>
</section>
<p>EventCount会递增，上位机可以通过该值是否连续递增来确认是否丢事件，以及丢了多少个事件。</p>
<h1>四. <strong>总结</strong></h1>
<p>以上分析了Tracealyzer的发送到上位机的事件记录是如何组织的，基于此就可以手动解析事件信息方便调试分析。甚至可以自己开发类似的GUI或者其他测试分析工具。</p>
<p> </p>
<p> </p>
<p> </p>
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