[maemo-developers] Out Of Memory handling in Maemo

[From: Karthik Murugesan]

Hi Eero,
     [Karthik] Thanks for your reply.

    I think ke-recv and AFAIK it doesn't use polling.
    [Karthik] What is ke-recv. Is it a closed source module? Can you
point me to some next level entry  point in the open code?

It tells at which point kernel should start denying memory allocations
from processes.  Processes exempted from OOM-killing are exempted also
from this.
    [Karthik] But how the kernel decides which process is exempted
from OOM-killing.  How can I change it.

    [Karthik] Also, till I am not clear which part of code actually
does the termination of the application and which raises the dbus
signal. Can you point me to some source code where I can refer.

Thanks
Karthik




-----Original Message-----
From: Eero Tamminen [mailto:eero.tamminen at nokia.com]
Sent: Tuesday, February 12, 2008 11:47 PM
To: ext Karthik Murugesan
Cc: maemo-developers at maemo.org
Subject: Re: Out Of Memory handling in Maemo

Hi,

ext Karthik Murugesan wrote:
> Hello all,
>     I am trying to understand Out of Memory Handling in Maemo for my
> thesis. As per the my understanding (based on the documentation  and
> browsing through libosso code). some module raises the  Dbus signals
> com.nokia.ke_recv.lowmem_on/lowmem_off  which is dispatched via DBUS
> to some other module( WM or AS) which does the actual termination of
> the LRU application based on the hibernation mode.
>
>    But I am not able to correlate on who raises the lowmem_on/off dbus
> signal and which function/module actually kills the application.
>
>    Is "/proc/sys/vm/lowmem_notify_high" used to listen for low memory
> conditions? If yes, How (by polling?) and which module does it.

I think ke-recv and AFAIK it doesn't use polling.


>    Whats the purpose of "/proc/sys/vm/lowmem_deny_watermark"? Is it to
> prevent launching new applications?

It tells at which point kernel should start denying memory allocations
from processes.  Processes exempted from OOM-killing are exempted
also from this.


>    I will really thankful, if someone can provide me some pointers in
> the code/guidance regarding this.


	- Eero