OVS L2 agent polling is too cpu intensive
Bug #1177973 reported by
Maru Newby
This bug affects 11 people
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
neutron |
Fix Released
|
Medium
|
Maru Newby | ||
Havana |
Fix Released
|
Medium
|
Terry Wilson |
Bug Description
On a Devstack-deployed, single-node install, the ovs l2 agent is using an order of magnitude more cpu than any other service. On a nested-virt VM running on a 2.5GHz host, with no VM's provisioned:
- WIth L2 agent running, 10-100% cpu usage recorded, averaging ~40%
- With L2 agent stopped, 0-10% cpu usage recorded
Casual inspection with something like top or htop will show the excessive cpu usage, but won't give a good indication of the culprit. Enabling the CUTIME and CSTIME stats is necessary to highlight the problem, as all the time taken by the agent is in subprocess-invoked polling whose execution time is not directly included in the parent's cpu usage.
description: | updated |
Changed in quantum: | |
status: | New → Confirmed |
Changed in quantum: | |
assignee: | nobody → Maru Newby (maru) |
tags: | added: ovs |
Changed in quantum: | |
importance: | Undecided → Medium |
Changed in neutron: | |
assignee: | Francois Eleouet (fanchon) → nobody |
Changed in neutron: | |
assignee: | nobody → Maru Newby (maru) |
milestone: | none → havana-3 |
Changed in neutron: | |
milestone: | havana-3 → havana-rc1 |
tags: | added: havana-rc-potential |
Changed in neutron: | |
milestone: | havana-rc1 → none |
tags: |
added: havana-backport-potential removed: havana-rc-potential |
tags: | removed: havana-backport-potential |
Changed in neutron: | |
milestone: | none → icehouse-1 |
Changed in neutron: | |
status: | Fix Committed → Fix Released |
tags: | added: havana-backport-potential |
tags: | removed: havana-backport-potential |
tags: | removed: in-stable-havana |
Changed in neutron: | |
milestone: | icehouse-1 → 2014.1 |
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The current polling-based checks for ovs bridge changes would ideally be replaced by something event-based.