Open Stack

Hi, I'd like you to take a look at this patch for potential
DocImpact.
https://review.openstack.org/27160

Log:
commit aaeb283f7cb5f73ac0049d662326c537dd56661d
Author: Alvaro Lopez Garcia <aloga at ifca.unican.es>
Date:   Thu Apr 18 17:28:27 2013 +0200

    Normalize the weights instead of using raw values.
    
    The weight system is being used by the scheduler and the cells code.
    
    Currently the weight system is using the raw values instead of normalizing
    them. This makes difficult to properly use multipliers for establishing
    the relative importance between two wheighers (one big magnitude could
    shade a smaller one).
    
    This commit introduces weight normalization so that we can apply
    multipliers easily. All the weights for an object will be normalized
    between 0.0 and 1.0 before being sumed up, so that the final weight
    for a host will be:
    
        weight = w1_multiplier * norm(w1) + w2_multiplier * norm(w2) + ...
    
    The RAMWeigher and RamByInstanceTypeWeigher have been modified so as to
    introduce a new "ram_weight_inverse" flag. Before, these weighers stated
    that to change the behaviour to "stacking" instead of "spreading", a
    negative multiplier would do the trick but this is not true when using
    more that one weigher.
    
    The MuteChildWeigher does not need anymore the 'mute_weight_value'.
    
    Partially implements blueprint normalize-scheduler-weights
    DocImpact
    
    TODO: enforce the weighers to implement a multiplier.
    
    Change-Id: I81bf90898d3cb81541f4390596823cc00106eb20