c 语言使用lttng

Posted 2021-02-19 rongfengliang

以下内容来自lttng 官方文档，主要是学习记录

创建tracepoint

• hello-tp.h

#undef TRACEPOINT_PROVIDER

#define TRACEPOINT_PROVIDER hello_world

?

#undef TRACEPOINT_INCLUDE

#define TRACEPOINT_INCLUDE "./hello-tp.h"

?

#if !defined(_HELLO_TP_H) || defined(TRACEPOINT_HEADER_MULTI_READ)

#define _HELLO_TP_H

?

#include <lttng/tracepoint.h>

?

TRACEPOINT_EVENT(

    hello_world,

    my_first_tracepoint,

    TP_ARGS(

        int, my_integer_arg,

        char*, my_string_arg

    ),

    TP_FIELDS(

        ctf_string(my_string_field, my_string_arg)

        ctf_integer(int, my_integer_field, my_integer_arg)

    )

)

?

#endif /* _HELLO_TP_H */

?

#include <lttng/tracepoint-event.h>

 

• hello-tp.c

#define TRACEPOINT_CREATE_PROBES

#define TRACEPOINT_DEFINE

?

#include "hello-tp.h"

• 构建

gcc -c -I. hello-tp.c

• c 应用
  hello.c

#include <stdio.h>

#include "hello-tp.h"

?

int main(int argc, char *argv[])

{

    int x;

?

    puts("Hello, World!
Press Enter to continue...");

?

    /*

     * The following getchar() call is only placed here for the purpose

     * of this demonstration, to pause the application in order for

     * you to have time to list its tracepoints. It‘s not needed

     * otherwise.

     */

    getchar();

?

    /*

     * A tracepoint() call.

     *

     * Arguments, as defined in hello-tp.h:

     *

     * 1. Tracepoint provider name   (required)

     * 2. Tracepoint name            (required)

     * 3. my_integer_arg             (first user-defined argument)

     * 4. my_string_arg              (second user-defined argument)

     *

     * Notice the tracepoint provider and tracepoint names are

     * NOT strings: they are in fact parts of variables that the

     * macros in hello-tp.h create.

     */

    tracepoint(hello_world, my_first_tracepoint, 23, "hi there!");

?

    for (x = 0; x < argc; ++x) {

        tracepoint(hello_world, my_first_tracepoint, x, argv[x]);

    }

?

    puts("Quitting now!");

    tracepoint(hello_world, my_first_tracepoint, x * x, "x^2");

?

    return 0;

}

 

• 构建

gcc -c hello.c 

• 链接应用

gcc -o hello hello.o hello-tp.o -llttng-ust -ldl

• 构建流程

 

 

 

追踪应用

• 启动应用

./hello world and beyond

• 启动 session daemon

lttng-sessiond --daemonize

• 查看tracepoint

lttng list --userspace

• 创建会话

lttng create my-user-space-session

• 创建event规则

lttng enable-event --userspace hello_world:my_first_tracepoint

• 启动

lttng start

• 操作
  输入enter，停止应用
• 停止追踪

 

lttng destroy

• 查看

babeltrace ~/lttng-traces/my-user-space-session*

• 效果

 

 

说明

对于构建我们需要安装devel包，这个通过efficios提供的yum包就包含了

参考资料

https://lttng.org/docs/v2.12/#doc-tracing-your-own-user-application