[Samba] limit samba page cache in linux

[ajay kanala]

On Thu, Jun 12, 2014 at 1:55 AM, Volker Lendecke <Volker.Lendecke at sernet.de>
wrote:

> 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.
>
> Hmm.
It looks you are right. Tried various tricks but kernel simply is
uncontrollable. Havent tried with mmap option. Will try this to see
behavior.

Volker
>
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