[Beowulf] Clustering VPS servers

[Jonathan Aquilina]

That is the whole reason even on my VPS I would consider recompiling a
kernel. Or at least compiling it on a test virtual server then applying it
to all other vps's I have

Thanks for the insight here :) I think I'll experiment with my netbook with
another recompile even more slimmed down hopefully.

-----Original Message-----
From: Mark Hahn [mailto:hahn at mcmaster.ca] 
Sent: 24 March 2013 18:22
To: Jonathan Aquilina
Cc: 'Beowulf Mailing List'
Subject: RE: [Beowulf] Clustering VPS servers

> What I am not understanding is the difference between using a 
> monolithic style kernel with everything compiled in vs. modules. Is 
> there a lower memory footprint if modules are used.

modules do have a marginally higher overhead (as well as potentially a
slightly slower layout in memory.)  but if your system has only the
features/drivers you need, it won't make any real difference whether
monolithic or modular.  the real issue is that a distro kernel will have a
lot of stuff compiled into it that you don't need, and will probably also be
compiled for a generic x86.

but the memory used by modules tends to be quite small - do lsmod, and see
that they're mostly something like 20KB, with occasional big ones (graphics
drivers, etc) that don't usually break 1MB.
4 MB on my 4GB laptop (fedora 17).  on a centos 6 cluster node with lots of
pointless modules, it's 8MB out of 32GB.

so memory really isn't the issue.  it's not clear to me whether there are
other factors that would produce noticable cpu/performance benefits.
compiling for cpu families sounds plausible, but since the kernel is rarely
compute-bound.  (the previous mention of using updated drivers makes a lot
more sense.)