Open Stack

Hi, I'd like you to take a look at this patch for potential
documentation impact.
https://review.openstack.org/9540

Log:
commit a69f660a7e4aace43631216e9b384c5cb59976fe
Author: Brian Elliott <brian.elliott at rackspace.com>
Date:   Thu Jun 21 00:44:24 2012 +0000

    Adds generic retries for build failures.
    
    Add a generic scheduler retry for build failures.  Failed
    build requests get casted back to scheduler for retry until
    success or the maximum number of attempts is reached. The
    number of attempts to make is configurable or can be
    simply set to 1 to disable retries altogether.
    
    There is an associated cost function, retry_host_cost_fn, to
    de-emphasize re-scheduling to the same host.
    
    Partially implements blueprint: scheduler-resource-race
    
    DocImpact:
    
    Adds a new capability to filter scheduler to enable retries of
    scheduling requests.
    
    1) New flag: scheduler_max_attempts (int) - Number of attempts to make
    to schedule an instance before giving up and settting the instance to
    error.
    2) New filter scheduler cost function:
        nova.scheduler.least_cost.retry_host_cost_fn -
    
        Adds additional cost for retrying scheduling at a host that was
        already used for a previous scheduling attempt.
    
        retry_host_cost_fn_weight is the associated FLAG to configure
        weight.
    
    Change-Id: I1127caeed4418c75372a42ca7fafacb4f061ffe3