Comment 8 for bug 1427893

Reviewed: https://review.openstack.org/196699
Committed: https://git.openstack.org/cgit/stackforge/os-ansible-deployment/commit/?id=b95827f35167ed845e66b4f7084ac95a2ff0d8aa
Submitter: Jenkins
Branch: master

commit b95827f35167ed845e66b4f7084ac95a2ff0d8aa
Author: kevin <email address hidden>
Date: Mon Jun 29 09:53:56 2015 -0500

    Added openstack_kernel options for gc_thresh

    This commit adds to the openstack_kernel_options to set the
    "net.ipv4/6.neigh.default.gc_thresh*" values according to how much ram
    is available on the box.

    How this is being defined:
    The change brings with it a filter to find the closest power of 2 from the
    amount of ram discovered on the target host. If facts are disabled when the
    role is called a default value of 1024 will be used. The `set_gc_val`, when
    computed, has a max value of 8192. For both ipv4/6 thresh1 is half the
    `set_gc_val` thresh2 is computed value, and finally both
    thresh3/router.gc_thresh are double the `set_gc_val`.

    The changes here should provide for a more scalable neutron networking
    environment by default while also ensuring that the values computed are sane.
    Additionallyi, should the user want to define their own values they can do so by
    simply overriding the `set_gc_val`.

    Change-Id: Ic5fd7ebdac009fa1472aeb0b0666f9b2611a31d7
    Closes-Bug: #1427893