linux-kernel - Re: detecting kernel mem leak

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Date:	Fri, 16 May 2008 10:58:48 +0200
From:	Stéphane ANCELOT <sancelot@...e.fr>
To:	Christoph Lameter <clameter@....com>
Cc:	Pekka Enberg <penberg@...helsinki.fi>, linux-kernel@...r.kernel.org
Subject: Re: detecting kernel mem leak

Christoph Lameter a écrit :
> On Tue, 13 May 2008, Stéphane ANCELOT wrote:
>
>   
>> I kept my kernel running with few applications for 5 days , doing
>> nothing more than backing up few kb of data on disk and refresh few X apps.
>>
>> Ater five days the global memory available go down from 24Mb to 8Mb ...
>>     
>
> That is normal. Linux tries to put all memory to use and will free on 
> demand.
>
>   
>> The are some signifiant changes in slabinfo but now, I do not know where
>> to search ?
>>     
>
> Compile the slabinfo tool.
>
> gcc -o slabinfo linux/Documentation/vm/slabinfo.c
>
> Then you can do
>
> slabinfo -T
>
> to get an overview of how much is used by slabs. But I do not see that 
> slabs are using an excessive amount. So toying around with slabinfo is 
> not going to get you anywhere.
>
>   
1) slabinfo  tells me SYSFS support for SLUB not active

In the kernel, there is SLAB or SLUB , my kernel is at this time 
configured for SLAB allocator.

it is documented SLUB minimizes cache line usage.
Do you think I have to switch to SLUB ?

2) regarding memory debugging, your reply and some mesages told it was 
normal the memory was growing (with ext3 buffer_heads...) and released 
on demand.
 This sounds to me it becomes VERY VERY difficult telling if my system 
is STABLE or NOT. Is there a way to bypass it ?
I assume I have to do some kind of small program trying to allocate 
almost the full remaining memory available at startup to empty caches ?

Best Regards
Steph

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