too much 2M hugepages reserved

[cheng li]

Env: ISO built on 11 April. Simplex AIO on libvirt VM, vswitch_type = ovs-dpdk

After deployment/apply, the VM is slow, and finally doesn't response.
Reboot doesn't resolve this problem.
After investigation, I find this happens because of low memory available.

I find that 6554 x 2M hugepages are reserved, it's more than 10GB memory.
I can see only 512 x 2M is used by ovs-dpdk. I lowered the hugepages to 1024, no such issue anymore.

[Frank Miller (sensfan22)]

StarlingX is designed by default to allocate all memory as 2M hugepages minus the memory reserved for the platform (including ovs-dpdk). Users are expected to use servers that have enough memory to run a StarlingX software load.

[cheng li (chengli3)]

Seems so little memory for StarlingX software load. I would suggest to allocate more memory for StartlingX software load.

[Al Bailey (albailey1974)]

Investigating 2 changes to address this
1) Not allocating hugepages (by default) when running in vbox.
2) Increasing platform memory available.

Note: The vbox change is not specific to the environment where this bug was detected.

[Frank Miller (sensfan22)]

This LP should only address item #1 where code is updated to not allocate hugepages by default for virtual environments. (Item #2 should be done in a separate LP.)

[Frank Miller (sensfan22)]

Marking release gating as StarlingX developers require a working virtual environment for development.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/656788

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/656788
Committed: https://git.openstack.org/cgit/starlingx/config/commit/?id=e51976083e6042546b1922e8a00bbb2e86e21423
Submitter: Zuul
Branch: master

commit e51976083e6042546b1922e8a00bbb2e86e21423
Author: Tao Liu <email address hidden>
Date: Thu May 2 10:45:11 2019 -0400

    Disable pre-allocation of 2M hugepages on VBox

    Slow performance was observed in vbox with the default
    2M hugepages allocation.

    This update disables the default 2M hugepages allocation
    in vbox. Users are expected to allocate desired huge pages
    via CLI or Horizon.

    In addition, the default platform reserved memory has been
    increased to 2500M on the worker nodes running in vbox.

    Fixes-Bug: 1825814

    Change-Id: I2558bcde76a23f1293e07486dbbe5a4b6f91db2f
    Signed-off-by: Tao Liu <email address hidden>