Inactive memory keep growing and how to release it?

[Simon Jeons]

On 03/14/2013 06:14 PM, Michal Hocko wrote:
> On Mon 04-03-13 17:52:22, Lenky Gao wrote:
>> 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:
> How did you try to reclaim the memory? How much memory is still free?
> Are you above watermaks (/proc/zoneinfo will tell you more)
>
>> # 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.
> This could be related to the memory fragmentation and your kernel seem
> to be too large to have memory compaction which helps a lot in that
> area.
>
>> Can you give some tips to avoid this?
> One way would be to increase /proc/sys/vm/min_free_kbytes which will
> enlarge watermaks so the reclaim starts sooner.
>   
>> 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
> This is really an old kernel and also a distribution one which might
> contain a lot of patches on top of the core kernel. I would suggest to
> contact Redhat or try to reproduce the issue with the vanilla and

What's the meaning of vanilla?

> up-to-date kernel and report here.