PHP-FPM no cache

[HTF]

Hello,

I've enabled caching on php scripts as below but it looks like the
server is not caching at all:

http {
  fastcgi_cache_path   /tmp/cache  levels=1:2
                       keys_zone=tmp:10m
                       inactive=5m;
 
  server {
    location / {
      ...
      fastcgi_cache   tmp;
      fastcgi_cache_valid   any      1h;
      fastcgi_cache_min_uses  1;
      ...
    }
  }
}

- but the caching directory is totally empty (nginx has write privileges
as it was created by nginx itself during reload)
- I haven't noticed any performance improvements by running apache
benchmark from different machine

Logs:

2011/07/04 07:53:59 [notice] 1082#0: start cache manager process 1088
2011/07/04 07:53:59 [notice] 1082#0: start cache loader process 1089
2011/07/04 07:54:59 [notice] 1089#0: http file cache: /tmp/cache 0.000M,
bsize: 4096
2011/07/04 07:54:59 [notice] 1082#0: signal 17 (SIGCHLD) received
2011/07/04 07:54:59 [notice] 1082#0: cache loader process 1089 exited
with code 0
2011/07/04 07:54:59 [notice] 1082#0: signal 29 (SIGIO) received

OS: CentOS 5.6
Nginx version: nginx/0.8.54

Could you help me to solve this please.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,211926,211926#msg-211926