Comment 4 for bug 1653880

Reviewed: https://review.openstack.org/416524
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=67e334b81c4038f2cf210e1410b774f9b19fe10e
Submitter: Jenkins
Branch: stable/mitaka

commit 67e334b81c4038f2cf210e1410b774f9b19fe10e
Author: Kevin Benton <email address hidden>
Date: Tue Jan 3 18:10:36 2017 -0800

    Reduce IP link show calls for SR-IOV scan loop

    The device scanning logic was calling 'ip link show' for every
    vf_index on the system, which was taking an excessive amount of
    time an CPU cycles on very dense SR-IOV servers (>64 interfaces).
    This was being executed every 2 seconds so it would cause the
    agent to take a large percentage of the CPU time.

    This patch adjusts the logic to use two 'ip link show' commands for
    checking all of the operations in a single get_assigned_devices_info
    call.

    Conflicts:
      neutron/tests/unit/plugins/ml2/drivers/mech_sriov/agent/test_eswitch_manager.py

    Closes-Bug: #1653880
    Change-Id: I361caaf7f70580ee8c7b48a4a9c9477bdefd8b4b
    (cherry picked from commit 9a022e7d7b85b7c21cf26698fe59c818c4577194)