Inactive memory keep growing and how to release it?

[Lenky Gao]

Hi,

When i just run a test on Centos 6.2 as follows:

#!/bin/bash

while true
do

	file="/tmp/filetest"

	echo $file

	dd if=/dev/zero of=${file} bs=512 count=204800 &> /dev/null

	sleep 5
done

the inactive memory keep growing:

#cat /proc/meminfo | grep Inactive\(fi
Inactive(file):   420144 kB
...
#cat /proc/meminfo | grep Inactive\(fi
Inactive(file):   911912 kB
...
#cat /proc/meminfo | grep Inactive\(fi
Inactive(file):  1547484 kB
...

and i cannot reclaim it:

# cat /proc/meminfo | grep Inactive\(fi
Inactive(file):  1557684 kB
# echo 3 > /proc/sys/vm/drop_caches
# cat /proc/meminfo | grep Inactive\(fi
Inactive(file):  1520832 kB

I have tested on other version kernel, such as 2.6.30 and .6.11, the
problom also exists.

When in the final situation, i cannot kmalloc a larger contiguous
memory, especially in interrupt context.
Can you give some tips to avoid this?

PS:
# uname -a
Linux localhost.localdomain 2.6.32-220.el6.x86_64 #1 SMP Tue Dec 6
19:48:22 GMT 2011 x86_64 x86_64 x86_64 GNU/Linux



--
Regards,

Lenky