> For the complete documentation index, see [llms.txt](https://book.bsdcn.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://book.bsdcn.org/man/man4/dtrace_io.4.md).

# dtrace\_io.4

`dtrace_io` — 用于跟踪磁盘 I/O 相关事件的 DTrace 提供者

## 名称

`dtrace_io`

## 概要

`Fn io:::start struct bio * struct devstat * Fn io:::done struct bio * struct devstat *`

## 描述

`io` 提供者允许跟踪磁盘 I/O 事件。Fn io:::start 探测在 I/O 请求即将发送到 [disk(9)](/man/man9/disk.9.md) 对象的后端驱动时触发。这发生在对请求执行所有 GEOM(4) 转换之后。Fn io:::done 探测在 I/O 请求完成时触发。两个探测都接受表示 I/O 请求的 `struct bio *` 作为第一个参数。第二个参数是底层 [disk(9)](/man/man9/disk.9.md) 对象的 `struct devstat *`。

## 参数

`struct bio` 的字段在 [g\_bio(9)](/man/man9/g_bio.9.md) 手册页中描述，`struct devstat` 的字段在 [devstat(9)](/man/man9/devstat.9.md) 手册页中描述。`bufinfo_t` 和 `devinfo_t` D 类型的转换器定义在 **/usr/lib/dtrace/io.d** 中。

## 文件

**`/usr/lib/dtrace/io.d`** `io` 提供者的 DTrace 类型和转换器定义。

## 实例

以下脚本按磁盘设备显示每个进程的总 I/O 分解：

```sh
#pragma D option quiet
io:::start
{
        @[args[1]->device_name, execname, pid] = sum(args[0]->bio_length);
}
END
{
        printf("%10s %20s %10s %15sn", "DEVICE", "APP", "PID", "BYTES");
        printa("%10s %20s %10d %15@dn", @);
}
```

## 兼容性

此提供者与 Solaris 中的 `io` 提供者不兼容，因为其探测使用原生 FreeBSD 参数类型。

## 参见

[dtrace(1)](/man/man1/dtrace.1.md), [devstat(9)](/man/man9/devstat.9.md), [SDT(9)](https://github.com/FreeBSD-Ask/freebsd-man-sc/tree/main/man9/sdt.9.md)

## 历史

`io` 提供者首次出现于 FreeBSD 9.2 和 10.0。

## 作者

本手册页由 Mark Johnston <markj@FreeBSD.org> 编写。

## 缺陷

Fn io:::wait-start 和 Fn io:::wait-done 探测目前在 FreeBSD 上未实现。


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:

```
GET https://book.bsdcn.org/man/man4/dtrace_io.4.md?ask=<question>&goal=<endgoal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.