[openstack-dev] Performance Regression in Neutron/Havana compared to Quantum/Grizzly

Nathani, Sreedhar (APS) sreedhar.nathani at hp.com
Thu Dec 5 13:23:19 UTC 2013

Hello Marun,

Please find the details about my setup and tests which i have done so far

  - One Physical Box with 16c, 256G memory. 2 VMs created on this Box - One for Controller and One for Network Node
  - 16x compute nodes (each has 16c, 256G memory)
  - All the systems are installed with Ubuntu Precise + Havana Bits from Ubuntu Cloud Archive

Steps to simulate the issue
  1) Concurrently create 30 Instances (m1.small) using REST API with mincount=30
  2) sleep for 20min and repeat the step (1)

Issue 1
In Havana, once we cross 150 instances (5 batches x 30) during 6th batch some instances are going into ERROR state
due to network port not able to create and some instances are getting duplicate IP address

Per Maru Newby this issue might related to this bug

I have done the similar with Grizzly on the same environment 2 months back, where I could able to deploy close to 240 instances without any errors
Initially on Grizzly also seen the same behavior but with these tunings based on this bug
https://bugs.launchpad.net/neutron/+bug/1160442, never had issues (tested more than 10 times)
       sqlalchemy_pool_size = 60
       sqlalchemy_max_overflow = 120
       sqlalchemy_pool_timeout = 2
       agent_down_time = 60
       report_internval = 20

In Havana, I have tuned the same tunables but I could never get past 150+ instances. Without the tunables I could not able to get past
100 instances. We are getting many timeout errors from the DHCP agent and neutron clients

NOTE: After tuning the agent_down_time to 60 and report_interval to 20, we no longer getting these error messages
   2013-12-02 11:44:43.421 28201 WARNING neutron.scheduler.dhcp_agent_scheduler [-] No more DHCP agents
   2013-12-02 11:44:43.439 28201 WARNING neutron.scheduler.dhcp_agent_scheduler [-] No more DHCP agents
   2013-12-02 11:44:43.452 28201 WARNING neutron.scheduler.dhcp_agent_scheduler [-] No more DHCP agents

In the compute node openvswitch agent logs, we see these errors repeating continuously

2013-12-04 06:46:02.081 3546 TRACE neutron.plugins.openvswitch.agent.ovs_neutron_agent Timeout: Timeout while waiting on RPC response - topic: "q-plugin", RPC method: "security_group_rules_for_devices" info: "<unknown>"
and WARNING neutron.openstack.common.rpc.amqp [-] No calling threads waiting for msg_id

DHCP agent has below errors

2013-12-02 15:35:19.557 22125 ERROR neutron.agent.dhcp_agent [-] Unable to reload_allocations dhcp.
2013-12-02 15:35:19.557 22125 TRACE neutron.agent.dhcp_agent Timeout: Timeout while waiting on RPC response - topic: "q-plugin", RPC method: "get_dhcp_port" info: "<unknown>"

2013-12-02 15:35:34.266 22125 ERROR neutron.agent.dhcp_agent [-] Unable to sync network state.
2013-12-02 15:35:34.266 22125 TRACE neutron.agent.dhcp_agent Timeout: Timeout while waiting on RPC response - topic: "q-plugin", RPC method: "get_active_networks_info" info: "<unknown>"

In Havana, I have merged the code from this patch and set api_workers to 8 (My Controller VM has 8cores/16Hyperthreads)

After this patch and starting 8 neutron-server worker threads, during the batch creation of 240 instances with 30 concurrent requests during each batch,
238 instances became active and 2 instances went into error. Interesting these 2 instances which went into error state are from the same compute node.

Unlike earlier this time, the errors are due to 'Too Many Connections' to the MySQL database.
2013-12-04 17:07:59.877 21286 AUDIT nova.compute.manager [req-26d64693-d1ef-40f3-8350-659e34d5b1d7 c4d609870d4447c684858216da2f8041 9b073211dd5c4988993341cc955e200b] [instance: c14596fd-13d5-482b-85af-e87077d4ed9b] Terminating instance
2013-12-04 17:08:00.578 21286 ERROR nova.compute.manager [req-26d64693-d1ef-40f3-8350-659e34d5b1d7 c4d609870d4447c684858216da2f8041 9b073211dd5c4988993341cc955e200b] [instance: c14596fd-13d5-482b-85af-e87077d4ed9b] Error: Remote error: OperationalError (OperationalError) (1040, 'Too many connections') None None

Need to back port the patch 'https://review.openstack.org/#/c/37131/' to address the Neutron Scaling issues in Havana.
Carl already back porting this patch into Havana  https://review.openstack.org/#/c/60082/ which is good.

Issue 2
Grizzly :
During the concurrent instance creation in Grizzly, once we cross 210 instances, during subsequent 30 instance creation some of
the instances could not get their IP address during the first boot with in first few min. Instance MAC and IP Address details
were updated in the dnsmasq host file but with a delay. Instances are able to get their IP address with a delay eventually.

If we reboot the instance using 'nova reboot' instance used to get IP Address.
* Amount of delay is depending on number of network ports and delay is in the range of 8seconds to 2min

Havana :
But in Havana only 81 instances could get the IP during the first boot. Port is getting created and IP address are getting allocated
very fast, but by the time port is UP its taking quite lot of time. Once the port is UP, Instances are able to send the DHCP Request
and get the IP address.

During the network port create and network port update, there are lot of 'security_group_rules_for_devices' messages. OVS Agents in the
compute nodes are getting Timeouts during "security_group_rules_for_devices"

Even though this issue exist in Grizzly but we observed this issue only after 200+ active instances (200 network ports), but in Havana
We are having these issues with less than 100 active ports.

In Havana, if we reboot the instance it's not able to get the IP Address even though its network port entry is already exist in
dnsmasq hosts file. We can't even ping the IP Address now which we were able to ping before the instance reboot. After restarting the
'neutron-dhcp-agent' service which will restart the 'dnsmasq' and reboot of the instance could get the IP

This clear shows we have performance regression in neutron/havana compared to quantum/grizzly

FYI, I attached the my notes for  one of the instance which could not get IP during first boot with this email

I am happy to share the results of my grizzly tests and logs during recent havana tests

Thanks & Regards,
Sreedhar Nathani
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