Re: wanna-build / how to sort packages on buildds?

[Tollef Fog Heen <tfheen@err.no>]

]] Andreas Barth 

Hi,

| Now my question is just: How to do that efficient? I.e. how would such
| a configuration file look like, and how the code to distribute the
| package on the most fitting buildd(s)? (I.e. it's better to waste 5
| out of 6 cores than to not build a package at all, but a package
| needing at least 1g ram can't build on a buildd with only 512mb - but
| no package should starve in the end.)
| 
| Ideas? Suggestions? Code?

Sounds like a variant of the knapsack problem.

I'd suggest something like:

- Have a mapping for buildds from resources to a value (this can just be
  a perl hash), this defines cores, amount of memory, etc.

- Each package has a minimum requirement for cpu, memory, etc, stored in a
  hash.  Store all the packages in a list.

- Sort the list, either according to a score which is a mix of cpu and
  memory and whatever other factors you want or first along the cpu
  axis, then along the memory axis, etc.  I suspect CPU and memory
  requirements are correlated, but not perfectly.

- Assign packages to buildds on a first-match basis.  That means you get
  the hardest packages done first.  The match has to make sure the
  buildd can actually build the package in question, of course.

Regards,
-- 
Tollef Fog Heen
UNIX is user friendly, it's just picky about who its friends are