How to force php-fpm to display slow log?

[agriz]

slowlog = /var/log/php-fpm/slow.log
request_slowlog_timeout = 1s
This following two lines are added in the php config file. Once it is added
and restart php-fpm, the slow.log file is created.

(request: "GET /index.php") executing too slow (1.072177 sec), logging
This error is displayed in error.log file of php-fpm. But there is no
additional details.

I am not able to trace which url is causing the trouble. It is codeigniter
framework. So I used the framework's benchmarking tool on all the methods
and found the execution is fast 0.004 to 0.01 for multiple test

What could be the possible reason for slow.log being empty? Is there a way
to get complete url in the error log for slow process?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,277048,277048#msg-277048