[Samba] limit samba page cache in linux

[Volker Lendecke]

On Sun, Jun 08, 2014 at 10:50:09AM +0200, Marc Muehlfeld wrote:
> Am 08.06.2014 09:37, schrieb ajay kanala:
> >> I am using linux kernel 3.10.12 (mips) on my embedded router box with
> >> samba server version: 3.0.24
> >
> > Any pointers?
> 
> 
> Normally I would first advice to upgrade to a Samba version that isn't 7
> years old. But as this is a embedded system, the situation is a bit
> different.
> 
> Kai Blin had a good presentation about Samba on µservers and the
> problems with recent Samba versions this year at the SambaXP:
> http://sambaxp.org/fileadmin/user_upload/SambaXP2014-AUDIO/thu/track1/sambaxp2014-thu-track1-Kai_Blin-uSamba-ScalingSambaDowntoMicroServers.mp3
> http://sambaxp.org/fileadmin/user_upload/SambaXP2014-DATA/thu/track1/Kai_Blin-Samba-ScalingSambaDowntoMicroServers.pdf
> 
> 
> Do you have the possibility to put a new Samba version on the box (maybe
> cross-compile)? What hardware is in your router?

My guess would be that a Samba upgrade would not help here.
This really sounds like a kernel problem to me. There is not
much that Samba can do. Maybe you can play some iptables
tricks to slow down file transfer (or use the HIGHLY
deprecated SO_SNDBUF and SO_RCVBUF socket options :-). But
Samba has no influence at all on the kernel memory
allocation. As indicated in another thread, "use mmap = no"
might help with Samba RSS, but this will also only shift
load from mmap'ed areas to the page cache.

Volker

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