[ovs-discuss] SR-IOV and storage over OVS

Kristoffer Egefelt kristoffer at itoc.dk
Thu Apr 18 11:56:05 UTC 2013


Hi Jesse

The system is still experiencing delay with more than 12000 flows.

Is there anything I can do about this - will getting a faster CPU help?

Thanks

On 17/04/2013, at 10.19.21, Kristoffer Egefelt <kristoffer at itoc.dk> wrote:

> OK - any suggestions on how to calculate the right value ?
> Could you explain the consequences of increasing this value ?
> 
> I ran 
> 
> ovs-vsctl set bridge xenbr0 other-config:flow-eviction-threshold=20000
> 
> the flows are stabilizing around 12-15000
> 
> Memory usage went from 12M to 14M - but the CPU load is still high > 94%
> 
> But the latency actually went back down from 1.5 seconds to 500ms, which is normal.
> 
> So this looks like it worked, even though the CPU usage remains high…
> 
> Thanks.
> 
> 
> On 16/04/2013, at 21.52.46, Jesse Gross <jesse at nicira.com> wrote:
> 
>> On Tue, Apr 16, 2013 at 3:47 AM, Kristoffer Egefelt <kristoffer at itoc.dk> wrote:
>>> Thanks Jesse,
>>> 
>>> I have a NAT firewall which logs something like this every second - OVS is processing ~400.000 packets/s - and I'm having issues with response times or even timeouts when load > 96%.
>>> Is there anything I can do about the latency/CPU usage, other than not running OVS on the NAT firewalls ?
>> 
>> There is a fair amount of work going on to improve in this area. If
>> you have a large number of established flows (instead of just new flow
>> setups), one thing that might help is to use
>> ovs-vsctl set bridge BR other-config:flow-eviction-threshold=X
>> to set the threshold above your expected number of sustained flows.
>> The default value is 1000.
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>> 
> 
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