# PHP 日志`%c`参数答疑
---
### 几个关键参数
* `%d`: 响应时间.
* `%C`: CPU处理时间占响应时间的百分比.
* `%M`: 峰值内存占用.
### 当时处理`%C`的几点疑惑
我在日志里面记录了`%C`, 查看英文解释如下**%CPU used by the request**, 一直以为是占用`CPU`的百分比, 查看日志就好奇为什么`CPU`动辄就占用超过`100%`.
后来查看了是**CPU处理时间占响应时间的百分比**.
#### 查看源码
[php源码](https://github.com/php/php-src), 文件路径`sapi/fpm/fpm/fpm_request.c
`
几个知识点:
##### `times`头文件
文件开头引用
```
#include
```
这个里面包含了`tms`的结构体.
```
The header shall define the structure tms, which is returned by times() and includes at least the following members:
clock_t tms_utime User CPU time.
clock_t tms_stime System CPU time.
clock_t tms_cutime User CPU time of terminated child processes.
clock_t tms_cstime System CPU time of terminated child processes.
clock_t times(struct tms *);
```
##### fpm_request 文件分析
在每次请求开始(`fpm_request_reading_headers`)和结束(`fpm_request_end`), 使用`times`获得当前进程`cpu`时间.
* `FPM_REQUEST_ACCEPTING`: Idle 空闲状态.
* `FPM_REQUEST_READING_HEADERS`: Reading headers 读取头信息.
*
