Open Stack

Try to disable GRO on interfaces. It's well known bug, causing significant
net performance drop in case of the GRE tunnels.

(Use ethtool)
On Nov 9, 2014 11:17 AM, "Alberto Molina Coballes" <alb.molina at gmail.com>
wrote:

> Hi,
>
> Debian testing (jessie) is now frozen, so it seems a good time to use it
> as a base for an OpenStack deployment. Debian jessie provides OpenStack
> Icehouse packages from official repos, backported repos are no longer
> needed.
>
> Installation procedure works fine in a setup with OVS and GRE tunnels, but
> a very low bandwidth is found between instances and routers. I know this is
> a frequently asked topic, but after reading some related threads and bugs,
> different causes and solutions where shown.
>
> In order to find the problem, several test with iperf has been made and
> proposed solutions applied:
>
> 1. Bandwidth between two instances running on the same compute node: 2.77
> Gbits/sec
> 2. Bandwidht between compute node and network node (Gigabith Ethernet
> used): 941 Mbits/sec
> 3. Bandwidth between an instance and a router running on network node: 200
> Kbits/sec !!!
> 4. After applying proposed solution setting instance MTU to 1454,
> identical result was obtained.
> 5. After applying proposed solution setting GRO off to physical interfaces
> (network and compute nodes), identical result was obtained.
>
> A solution was found here: https://bugs.launchpad.net/fuel/+bug/1256289
>
> 6. After setting tcp segmentation offload off in internal router interface:
>
> ip netns exec qrouter-XXXXXX ethtool -K qr-14460da5-08 tso off
>
> Bandwidth increased to 27 Mbits/sec
>
> 7. After setting  tcp segmentation offload off in the instance interface,
> a very good performance is achieved: 776 Mbits/sec.
>
> Solution found :), but the question is: What's the best way to implement
> it? It isn't a practical solution to modify instance Ethernet configuration
> after an instance is launched.
>
> Any tip on this?
>
> Thanks!
>
> Alberto
>
>
>
>
>
>
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