Effective effect of enabling Apache response time log directive

Question

What affects the response time (% D) of the LogFormat directive on Apache performance?

Response time is the time taken to complete the request in microseconds.

The response time can be included as follows:

#LogFormat "%h %l %u %t \"%r\" %>s %b"    # Default LogFormat
LogFormat "%h %l %u %t \"%r\" %>s %b %D"  # LogFormat including response time

I wrote a tool to monitor and analyze the performance of the backend script, apache-response-time , which requires response time data. I would like to warn potential users about how including this directive will affect Apache server performance.

Answer 1

, HTTP- - 1 addl gettimeofday() ( ), - . Apache , .

http://www.atl.lmco.com/projects/QoS/POSIX_html/index.html gettimeofday().