HarmonyHu 多思不如养志,多言不如守静,多才不如蓄德

Linux Event Tracing

2019-03-17

Tracepoints添加

参考 Tracepoints

1. 添加头文件

include/trace/events/sample.h

#undef TRACE_SYSTEM
#define TRACE_SYSTEM sample

#if !defined(_TRACE_SUBSYS_H) || defined(TRACE_HEADER_MULTI_READ)
#define _TRACE_SUBSYS_H

#include <linux/tracepoint.h>

DECLARE_TRACE(sample_event,
        TP_PROTO(int firstarg, struct task_struct *p),
        TP_ARGS(firstarg, p));

#endif /* _TRACE_SUBSYS_H */

/* This part must be outside protection */
#include <trace/define_trace.h>

2. 生成结点和导出

kernel/trace/trace_sample.c

#include <linux/string.h>
#include <linux/types.h>
#include <linux/module.h>

#define CREATE_TRACE_POINTS
#include <trace/events/sample.h>

EXPORT_TRACEPOINT_SYMBOL_GPL(sample_event);

3. 代码中调用tracepoint

#include <trace/events/smaple.h>

void somefunc(void)
{
  ...
  trace_sample_event(arg, task);
  ...
}

Event Tracing

参考 Event Tracing

1. 通过set_event使能

# enable
echo sample_event >> /sys/kernel/debug/tracing/set_event
# disable
echo '!sample_event' >> /sys/kernel/debug/tracing/set_event
# enable all
echo *:* >> /sys/kernel/debug/tracing/set_event
# enable one evnet all sub event
echo 'irq:*' >> /sys/kernel/debug/tracing/set_event

2. 通过enable使能

# enable                   
echo 1 > /sys/kernel/debug/tracing/events/sample/enable
# disable
echo 0 > /sys/kernel/debug/tracing/events/sample/enable
# enable某个sub event
echo 1 > /sys/kernel/debug/tracing/events/sample/sample_event/enable
# enable所有sub event
echo 1 > /sys/kernel/debug/tracing/events/enable

3. 查看tracing日志

cat /sys/kernel/debug/tracing/trace

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