Directio not working

Hi, from nginx wiki:

syntax: directio [size|off]
default: directio off
context: http, server, location
The directive enables use of flags O_DIRECT (FreeBSD, Linux), F_NOCACHE
(Mac OS X) or directio() function (Solaris) for reading files with size
greater than specified. This directive disables use of
sendfile for this
request. This directive may be useful for big files:
directio 4m;

I have in my config:
directio 0;

(I do not want to cache anything in ram)

But ater 5 mins of nginx running:

free -m
total used free shared buffers
Mem: 7994 1980 6014 0 255
-/+ buffers/cache: 691 7303

(cached is going up and up)

Is something else needed or is it just not working?

2.6.35-28-generic #50-Ubuntu SMP Fri Mar 18 18:42:20 UTC 2011 x86_64

Many thanks as always


This directive just sets when to use direct IO and when not to, it does
not affect the Nginx output buffers which are used when sendfile is
turned off.

Similarly, the cached value you see in free -m is the amount your OS use
for caching IO, not nginx. If you wish to turn this off you must do so
at the OS level.

Posted at Nginx Forum: