openstack team mailing list archive

[Vishvananda Ishaya <vishvananda@xxxxxxxxx>]

I believe it is safe to ignore the old leases.  If nova-network has been down for a while it could potentially be nice to refresh all of the leases that it knows about, but I don't think it will harm anything if you remove it.

Are you running flatdhcp with a single network host on a large install?  I would think that multi_host would be a better choice in that case.

There is also a potentially nasty performance issue in linux_net where it creates all of the leases.  It is a very expensive operation and needs to be reoptimized after the foreign keys were removed from the network tables. Currently it is doing 2 database for every active instance in the db.

Vish

On Mar 18, 2012, at 10:42 PM, Anton Blanchard wrote:

> 
> Hi,
> 
> We are seeing severe boot and delete performance issues with
> FlatDHPManager and a lot of instances.
> 
> If I have 200 instances running and boot 1 new instance a kill -HUP
> dnsmasq calls nova-dhcpbridge 201 times, 200 for the existing leases and
> once for the new one.
> 
> The 200 events for existing leases end up here in nova-dhcpbridge:
> 
> def old_lease(mac, ip_address):
>    """Update just as add lease."""
>    LOG.debug(_("Adopted old lease or got a change of mac"))
>    add_lease(mac, ip_address)
> 
> I'm not sure why we need to do this at all. The comment mentions
> tracking a change of MAC and yet add_lease doesn't seem to do anything
> with the MAC parameter.
> 
> I can fix my performance problem by ignoring any old leases, but I was
> hoping someone could explain what the purpose is here.
> 
> Anton
> 
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