[oe] Using bitbake in minimal chroot environment

[Mike Westerhof]

Frans Meulenbroeks wrote:
> 2010/2/15 Martin Jansa <martin.jansa at gmail.com>:
>>> Seems a good plan to me, please keep us posted.
>>> (actually I've been considering building in a minimalistic VM)
>> Well VM would be much slower..
> 
> Someone else told me the same today.
> What exactly causes this? I would expect I/O to be the differentiating
> factor as memory access and executing instructions should take the
> same time, shouldn't it?

I build in a VM often, and the difference is not very significant.  In
fact, I can't measure the difference in building SlugOS using the wall
clock.

I also tried placing all of my TMPDIR on a tmpfs on my 8GB RAM system,
and building SlugOS -- again, no difference compared to the normal SATA
hard drive for TMPDIR.

So my conclusion is that I/O is not the bottleneck for my OE builds, and
that's the only area where a VM is significantly different in terms of
performance (at least how I use VMs; perhaps other builds may observe
differences).

Before I ended up on my current contract, which locks me away behind
draconian firewalls, I used to take my autobuilder on the road with me
as a VM, building SlugOS and several of the OpenMoko distros -- I
heartily recommend that solution!

-Mike (mwester)