[vserver] Re: [Freedombox-discuss] [vserver] Re: A software architecture for the FreedomBox

From: Eugen Leitl <eugen_at_leitl.org>
Date: Thu 14 Apr 2011 - 07:32:45 BST
Message-ID: <20110414063245.GD23560@leitl.org>

----- Forwarded message from bertagaz@ptitcanardnoir.org -----

From: bertagaz@ptitcanardnoir.org
Date: Wed, 13 Apr 2011 23:04:53 +0200
To: freedombox-discuss@lists.alioth.debian.org
Subject: Re: [Freedombox-discuss] [vserver] Re: A software architecture for
        the FreedomBox

Hi,

On Wed, Apr 13, 2011 at 10:41:51PM +0200, Eugen Leitl wrote:
> ----- Forwarded message from Herbert Poetzl <herbert@13thfloor.at> -----
>
> From: Herbert Poetzl <herbert@13thfloor.at>
> Date: Wed, 13 Apr 2011 22:40:33 +0200
> To: Eugen Leitl <eugen@leitl.org>
> Cc: vserver@list.linux-vserver.org, Jonas Smedegaard <dr@jones.dk>,
> freedombox-discuss@lists.alioth.debian.org
> Subject: Re: [vserver] Re: [Freedombox-discuss] A software architecture for the FreedomBox
> User-Agent: Mutt/1.5.11
>
> On Wed, Apr 13, 2011 at 10:31:22PM +0200, Eugen Leitl wrote:
> > ----- Forwarded message from Jonas Smedegaard <dr@jones.dk> -----
> >
> > From: Jonas Smedegaard <dr@jones.dk>
> > Date: Wed, 13 Apr 2011 18:20:58 +0200
> > To: freedombox-discuss@lists.alioth.debian.org
> > Subject: Re: [Freedombox-discuss] A software architecture for the FreedomBox
> > User-Agent: Mutt/1.5.21 (2010-09-15)
> > Reply-To: freedombox-discuss@lists.alioth.debian.org
>
> > On 11-04-13 at 05:49pm, Eugen Leitl wrote:
> > > On Wed, Apr 13, 2011 at 05:06:23PM +0200, Rob van der Hoeven wrote:
>
> > > > One of the first things you have to do when building a
> > > > system like the FreedomBox is figure out the software
> > > > architecture. I have come up with an interesting
> > > > architecture that is made of Linux Containers (Virtual
>
> > > Using Linux vserver guests for service separation (jails on
> > > steroids) is an excellent idea, actually.
>
> > I find it interesting, but am sceptical: I believe each
> > jail consume separate memory for their libraries - i.e.
> > cannot benefit from shared libraries. So I worry about memory
> > consumption.
>
> mainly depends on the guest setup, assuming that the
> guests use identical libraries and the on disk data
> is properly unified, then both, the inode cache and
> the page mappings will use the very same memory

Vserver unification hasn't been something really solid in the past, often
brokeni, at least in Debian.

Note that the vserver patch support in Debian will stop with wheezy. LXC
might be a better choice in the long term.

> > On a related note I want to keep low the number of used library
> > environments - e.g. try to aim for...
>
> > * only one of libssl or gnutls fewest possible of Python,
> > * Perl, Bash, Ruby, PHP
>
> > ...especially for things running as daemons, but also for e.g.
> > cron-triggered scripts, as even temporary required memory might
> > not be available.
>
> sounds like a sane approach ... even the best sharing
> cannot help if you share huge amounts of data :)
>
> > I notice the test system uses swap. That is bad if using
> > internal flash disks as they wear much faster that way, and
> > swapping onto an external harddisk is not user-friendly:
> > Treating it as hot-plug then not only risk roccupting the data
> > files potentially being in the middle of a transaction but
> > crashes the whole system!
>
> why not simply turn swap off, there is no real need
> nowadays to enable swap, and if you really care to
> avoid OOM situations alltogether, disable memory
> overcommitment as well
>
> > - Jonas
>
> > --
> > * Jonas Smedegaard - idealist & Internet-arkitekt
> > * Tlf.: +45 40843136 Website: http://dr.jones.dk/
>
> > [x] quote me freely [ ] ask before reusing [ ] keep private
>
> > _______________________________________________
> > Freedombox-discuss mailing list
> > Freedombox-discuss@lists.alioth.debian.org
> > http://lists.alioth.debian.org/mailman/listinfo/freedombox-discuss
> >
> >
> > ----- End forwarded message -----
> > --
> > Eugen* Leitl leitl http://leitl.org
> > ______________________________________________________________
> > ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
> > 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE
>
> ----- End forwarded message -----
> --
> Eugen* Leitl leitl http://leitl.org
> ______________________________________________________________
> ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
> 8B29F6BE: 099D 78BA 2FD3 B014 B08A 7779 75B0 2443 8B29 F6BE
>
> _______________________________________________
> Freedombox-discuss mailing list
> Freedombox-discuss@lists.alioth.debian.org
> http://lists.alioth.debian.org/mailman/listinfo/freedombox-discuss

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----- End forwarded message -----

-- 
Eugen* Leitl leitl http://leitl.org
______________________________________________________________
ICBM: 48.07100, 11.36820 http://www.ativel.com http://postbiota.org
8B29F6BE: 099D 78BA 2FD3 B014 B08A  7779 75B0 2443 8B29 F6BE
Received on Thu Apr 14 07:33:00 2011
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