[Openstack] Directional network performance issues with Neutron + OpenvSwitch

Martinx - ジェームズ thiagocmartinsc at gmail.com
Fri Oct 25 16:28:26 UTC 2013


Here we go:

---
root at net-node-1:~# grep local_ip
/etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini
local_ip = 10.20.2.52

root at net-node-1:~# ip r | grep 10.\20
10.20.2.0/24 dev eth1  proto kernel  scope link  src 10.20.2.52
---

---
root at hypervisor-1:~# grep local_ip
/etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini
local_ip = 10.20.2.53

root at hypervisor-1:~# ip r | grep 10.\20
10.20.2.0/24 dev eth1  proto kernel  scope link  src 10.20.2.53
---

---
root at hypervisor-2:~# grep local_ip
/etc/neutron/plugins/openvswitch/ovs_neutron_plugin.ini
local_ip = 10.20.2.57

root at hypervisor-2:~# ip r | grep 10.\20
10.20.2.0/24 dev eth1  proto kernel  scope link  src 10.20.2.57
---

Each "ovs-vsctl show":

net-node-1: http://paste.openstack.org/show/49727/

hypervisor-1: http://paste.openstack.org/show/49728/

hypervisor-2: http://paste.openstack.org/show/49729/


Best,
Thiago


On 25 October 2013 14:11, Darragh O'Reilly <dara2002-openstack at yahoo.com>wrote:

>
> the uneven ssh performance is strange - maybe learning on the tunnel mesh
> is not stablizing. It is easy to mess it up by giving a wrong local_ip in
> the ovs-plugin config file. Check the tunnels ports on br-tun with
> 'ovs-vsctl show'. Is each one using the correct IPs? Br-tun should have N-1
> gre-x ports - no more! Maybe you can put 'ovs-vsctl show' from the nodes on
> paste.openstack if there are not to many?
>
> Re, Darragh.
>
>
>   On Friday, 25 October 2013, 16:20, Martinx - ジェームズ <
> thiagocmartinsc at gmail.com> wrote:
>
> I think can say... "YAY!!"    :-D
>
> With "LibvirtOpenVswitchDriver" my internal communication is the double
> now! It goes from ~200 (with LibvirtHybridOVSBridgeDriver) to *400Mbit/s*(with LibvirtOpenVswitchDriver)! Still far from 1Gbit/s (my physical path
> limit) but, more acceptable now.
>
> The command "ethtool -K eth1 gro off" still makes no difference.
>
> So, there is only 1 remain problem, when traffic pass trough L3 /
> Namespace, it is still useless. Even the SSH connection into my Instances,
> via its Floating IPs, is slow as hell, sometimes it just stops responding
> for a few seconds, and becomes online again "out-of-nothing"...
>
> I just detect a weird "behavior", when I run "apt-get update" from
> instance-1, it is slow as I said plus, its ssh connection (where I'm
> running apt-get update), stops responding right after I run "apt-get
> update" AND, *all my others ssh connections also stops working too!* For
> a few seconds... This means that when I run "apt-get update" from within
> instance-1, the SSH session of instance-2 is affected too!! There is
> something pretty bad going on at L3 / Namespace.
>
> BTW, do you think that a ~400MBit/sec intra-vm-communication (GRE tunnel)
> on top of a 1Gbit ethernet is acceptable?! It is still less than a half...
>
> Thank you!
> Thiago
>
> On 25 October 2013 12:28, Darragh O'Reilly <dara2002-openstack at yahoo.com>wrote:
>
> Hi Thiago,
>
> for the VIF error: you will need to change qemu.conf as described here:
> http://openvswitch.org/openstack/documentation/
>
> Re, Darragh.
>
>
>   On Friday, 25 October 2013, 15:14, Martinx - ジェームズ <
> thiagocmartinsc at gmail.com> wrote:
>
> Hi Darragh,
>
> Yes, Instances are getting MTU 1400.
>
> I'm using LibvirtHybridOVSBridgeDriver at my Compute Nodes. I'll check BG
> 1223267 right now!
>
>
> The LibvirtOpenVswitchDriver doesn't work, look:
>
> http://paste.openstack.org/show/49709/
>
> http://paste.openstack.org/show/49710/
>
>
> My NICs are "RTL8111/8168/8411 PCI Express Gigabit Ethernet", Hypervisors
> motherboard are MSI-890FXA-GD70.
>
> The command "ethtool -K eth1 gro off" did not had any effect on the
> communication between instances on different hypervisors, still poor,
> around 248Mbit/sec, when its physical path reach 1Gbit/s (where GRE is
> built).
>
> My Linux version is "Linux hypervisor-1 3.8.0-32-generic
> #47~precise1-Ubuntu", same kernel on Network Node" and others nodes too
> (Ubuntu 12.04.3 installed from scratch for this Havana deployment).
>
> The only difference I can see right now, between my two hypervisors, is
> that my second is just a spare machine, with a slow CPU but, I don't think
> it will have a negative impact at the network throughput, since I have only
> 1 Instance running into it (plus a qemu-nbd process eating 90% of its CPU).
> I'll replace this CPU tomorrow, to redo this tests again but, I don't think
> that this is the source of my problem. The MOBOs of two hypervisors
> are identical, 1 3Com (manageable) switch connecting the two.
>
> Thanks!
> Thiago
>
>
>  On 25 October 2013 07:15, Darragh O'Reilly <dara2002-openstack at yahoo.com>wrote:
>
> Hi Thiago,
>
> you have configured DHCP to push out a MTU of 1400. Can you confirm that
> the 1400 MTU is actually getting out to the instances by running 'ip link'
> on them?
>
> There is an open problem where the veth used to connect the OVS and Linux
> bridges causes a performance drop on some kernels -
> https://bugs.launchpad.net/nova-project/+bug/1223267 .  If you are using
> the LibvirtHybridOVSBridgeDriver VIF driver, can you try changing to
> LibvirtOpenVswitchDriver and repeat the iperf test between instances on
> different compute-nodes.
>
> What NICs (maker+model) are you using? You could try disabling any
> off-load functionality - 'ethtool -k <iface-used-for-gre>'.
>
> What kernal are you using: 'uname -a'?
>
> Re, Darragh.
>
> > Hi Daniel,
>
> >
> > I followed that page, my Instances MTU is lowered by DHCP Agent but, same
> > result: poor network performance (internal between Instances and when
> > trying to reach the Internet).
> >
> > No matter if I use
> "dnsmasq_config_file=/etc/neutron/dnsmasq-neutron.conf +
> > "dhcp-option-force=26,1400"" for my Neutron DHCP agent, or not (i.e. MTU
> =
> > 1500), the result is almost the same.
> >
> > I'll try VXLAN (or just VLANs) this weekend to see if I can get better
> > results...
> >
> > Thanks!
> > Thiago
>
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