Open Stack

On Mon, 2014-01-06 at 19:40 +0900, Isaku Yamahata wrote:
> On Fri, Dec 27, 2013 at 11:09:02AM +0100,
> Salvatore Orlando <sorlando at nicira.com> wrote:
> 
> > Hi,
> > 
> > We now have several patches under review which improve a lot how neutron
> > handles parallel testing.
> > In a nutshell, these patches try to ensure the ovs agent processes new,
> > removed, and updated interfaces as soon as possible,
> > 
> > These patches are:
> > https://review.openstack.org/#/c/61105/
> > https://review.openstack.org/#/c/61964/
> > https://review.openstack.org/#/c/63100/
> > https://review.openstack.org/#/c/63558/
> > 
> > There is still room for improvement. For instance the calls from the agent
> > into the plugins might be consistently reduced.
> > However, even if the above patches shrink a lot the time required for
> > processing a device, we are still hitting a hard limit with the execution
> > ovs commands for setting local vlan tags and clearing flows (or adding the
> > flow rule for dropping all the traffic).
> > In some instances this commands slow down a lot, requiring almost 10
> > seconds to complete. This adds a delay in interface processing which in
> > some cases leads to the hideous SSH timeout error (the same we see with bug
> > 1253896 in normal testing).
> > It is also worth noting that when this happens sysstat reveal CPU usage is
> > very close to 100%
> > 
> > From the neutron side there is little we can do. Introducing parallel
> > processing for interface, as we do for the l3 agent, is not actually a
> > solution, since ovs-vswitchd v1.4.x, the one executed on gate tests, is not
> > multithreaded. If you think the situation might be improved by changing the
> > logic for handling local vlan tags and putting ports on the dead vlan, I
> > would be happy to talk about that.
> 
> How about batching those ovsdb operations?
> Instead of issueing many ovs-vsctl command,
> ovs-vsctl -- command0 [args] -- command1 [args] -- ...
> 
> Then, the number of ovs-vsctl will be reduced and ovs-vsctl issues
> only single ovsdb transaction.

https://bugs.launchpad.net/neutron/+bug/1264608

:)

-jay