Re: P2P Guix package building and distribution

[Andreas Enge <andreas@enge.fr>]

Hello Christine,

Am Wed, Aug 21, 2024 at 06:07:58PM -0400 schrieb Christine Lemmer-Webber:
> >  1. Buying and hosting hardware:
> >      250k€ for hardware
> >      3k€/month (36k€/year)
> So I am guessing bandwith costs are significant but the 250k EUR for
> hardware indicates this is especially a build farm issue rather than a
> content distribution / bandwith issue.  (Do I have that right?)

to explain the figures, we counted 30 machines times 100€/month for
hosting, which is maybe what we could obtain if Aquilenet hosts them more
or less at cost for us. This includes bandwidth and electricity; from
what I understood, electricity is the major block, and it is directly
proportional to the number of machines. Bandwidth seems to be less of an
issue. First of all, it is computed somewhat strangely, like
"95% of the time you need to be below 1Gb/s, the remaining 5% you can be
above"; with bandwidth requirements for building coming in bursts
(sometimes inputs are downloaded, sometimes outputs are uploaded,
in-between there is computation without communication) adding a machine
might have the effect of smoothing out the distribution through the
law of large numbers without actually moving the 95-percentile.
And bandwidth is priced degressively.

This concerns bandwidth for building. Bandwidth for distribution is
proportional to the number of users, but so far has not been a bottleneck.
(Of course this will change when we get closer to world domination.)

> Okay, but what if instead I had the option to download something signed
> off by *all of* the MegaCloud build service and two "Guix Builders", and
> they all came to the same hash?

Would this not suppose that all these build instances are completely
disjoint from each other (like bordeaux or ci), and thus will have to
build everything from scratch? Since if a "Guix Builder" uses a MegaCloud
input, every build from then on is no more secure than a MegaCloud build.
Given the effort (in money and administrators' time) to run one build farm,
it does not look realistic that several people start their own build farm
at home.

Andreas