Finding a Keystone bug while benchmarking 20 node HA cloud performance at creating 400 VMs

(Contributed by Alexander Maretskiy, Mirantis)

Below we describe how we found a bug in Keystone and achieved 2x average performance increase at booting Nova servers after fixing that bug. Our initial goal was to benchmark the booting of a significant amount of servers on a cluster (running on a custom build of Mirantis OpenStack v5.1) and to ensure that this operation has reasonable performance and completes with no errors.

Goal

• Get data on how a cluster behaves when a huge amount of servers is started
• Get data on how good the neutron component is good in this case

Summary

• Creating 400 servers with configured networking
• Servers are being created simultaneously - 5 servers at the same time

Hardware

Having a real hardware lab with 20 nodes:

Vendor	SUPERMICRO SUPERSERVER
CPU	12 cores, Intel(R) Xeon(R) CPU E5-2620 v2 @ 2.10GHz
RAM	32GB (4 x Samsung DDRIII 8GB)
HDD	1TB

Cluster

This cluster was created via Fuel Dashboard interface.

Deployment	Custom build of Mirantis OpenStack v5.1
OpenStack release	Icehouse
Operating System	Ubuntu 12.04.4
Mode	High availability
Hypervisor	KVM
Networking	Neutron with GRE segmentation
Controller nodes	3
Compute nodes	17

Rally

Version

For this benchmark, we use custom Rally with the following patch:

https://review.openstack.org/#/c/96300/

Deployment

Rally was deployed for cluster using ExistingCloud type of deployment.

Server flavor

$ nova flavor-show ram64
+----------------------------+--------------------------------------+
| Property                   | Value                                |
+----------------------------+--------------------------------------+
| OS-FLV-DISABLED:disabled   | False                                |
| OS-FLV-EXT-DATA:ephemeral  | 0                                    |
| disk                       | 0                                    |
| extra_specs                | {}                                   |
| id                         | 2e46aba0-9e7f-4572-8b0a-b12cfe7e06a1 |
| name                       | ram64                                |
| os-flavor-access:is_public | True                                 |
| ram                        | 64                                   |
| rxtx_factor                | 1.0                                  |
| swap                       |                                      |
| vcpus                      | 1                                    |
+----------------------------+--------------------------------------+

Server image

$ nova image-show TestVM
+----------------------------+-------------------------------------------------+
| Property                   | Value                                           |
+----------------------------+-------------------------------------------------+
| OS-EXT-IMG-SIZE:size       | 13167616                                        |
| created                    | 2014-08-21T11:18:49Z                            |
| id                         | 7a0d90cb-4372-40ef-b711-8f63b0ea9678            |
| metadata murano_image_info | {"title": "Murano Demo", "type": "cirros.demo"} |
| minDisk                    | 0                                               |
| minRam                     | 64                                              |
| name                       | TestVM                                          |
| progress                   | 100                                             |
| status                     | ACTIVE                                          |
| updated                    | 2014-08-21T11:18:50Z                            |
+----------------------------+-------------------------------------------------+

Task configuration file (in JSON format):

{
   "NovaServers.boot_server": [
       {
           "args": {
               "flavor": {
                   "name": "ram64"
               },
               "image": {
                   "name": "TestVM"
               }
           },
           "runner": {
               "type": "constant",
               "concurrency": 5,
               "times": 400
           },
           "context": {
               "neutron_network": {
                   "network_ip_version": 4
               },
               "users": {
                   "concurrent": 30,
                   "users_per_tenant": 5,
                   "tenants": 5
               },
               "quotas": {
                   "neutron": {
                       "subnet": -1,
                       "port": -1,
                       "network": -1,
                       "router": -1
                   }
               }
           }
       }
   ]
}

The only difference between first and second run is that runner.times for first time was set to 500

Results

First time - a bug was found:

Starting from 142 server, we have error from novaclient: Error <class 'novaclient.exceptions.Unauthorized'>: Unauthorized (HTTP 401).

That is how a bug in Keystone was found.

action	min (sec)	avg (sec)	max (sec)	90 percentile	95 percentile	success	count
nova.boot_server total	6.507 6.507	17.402 17.402	100.303 100.303	39.222 39.222	50.134 50.134	26.8% 26.8%	500 500

Second run, with bugfix:

After a patch was applied (using RPC instead of neutron client in metadata agent), we got 100% success and 2x improved average performance:

action	min (sec)	avg (sec)	max (sec)	90 percentile	95 percentile	success	count
nova.boot_server total	5.031 5.031	8.008 8.008	14.093 14.093	9.616 9.616	9.716 9.716	100.0% 100.0%	400 400