Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/16221

Log:
commit 1d351de1024b87556cc162b980f157d7b3bf9983
Author: Chris Behrens <cbehrens at codestud.com>
Date:   Thu Nov 15 18:08:07 2012 +0000

    Cells: Add filtering and weight support
    
    This adds filtering and weighing support to the cells scheduler.
    
    Adds the following config options to the 'cells' group:
    
    scheduler_filter_classes -- list of filter classes
    scheduler_weight_classes -- list of weight classes
    
    Adds a couple of weighing modules as defaults (which removes the random
    cell selection):
    
    ram_by_instance_type: Select cells with the most capacity for the
    instance type being requested.
    weight_offset: Allows modifying the DB to weight a particular cell
    (useful for disabling a cell)
    
    Adds a filter class that allows specifying a scheduler hint to direct a
    build to a particular cell.
    
    DocImpact
    
    Change-Id: I027c5734e3d6134127fcd4dd28b8ff39047416dc