Open Stack

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

Log:
commit 9db74b55a75eee5a2826c17da1e824a8fb6d4f7b
Author: Alvaro Lopez Garcia <aloga at ifca.unican.es>
Date:   Thu Apr 18 17:28:27 2013 +0200

    Normalize the scheduler weights instead of using raw values.
    
    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) + ...
    
    Also, a new "ram_weight_inverse" flag has been introduced for the
    RAMWeigher. Before, the weigher 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.
    
    Partially implements blueprint normalize-scheduler-weights
    DocImpact
    
    TODO: enforce the weighers to implement a multiplier.
    
    Change-Id: I81bf90898d3cb81541f4390596823cc00106eb20