[ovs-discuss] Too many missed flows and high cpu usage

ananthan ananthannair935 at gmail.com
Mon May 27 13:52:47 UTC 2013


Hi,
   I am having high traffic vms running on Xenserver 6.0.2 with some vms
using more than 11mbps which include public and private traffic.
And because of this high traffic vms i am not able to run more than 2 vms
on single host as ovs-vswitchd struggles to process packet resulting in
heavy packet loss.
*
*
*OVS Version:*
*
*
*ovs 1.4.2*
*
*
system at xapi3:
lookups: hit:19216169494 *missed*:18847093088 *lost*:7227365
*flows:* 2581
port 0: xapi3 (internal)
port 1: eth1
port 2: eth0
port 4: xapi4 (internal)
port 9: vif6.0
port 14: vif12.0
port 19: vif16.0
port 20: vif17.0

may be because of this high miss rate ovs-vswitchd is consuming  80% CPU.

Can some one please clarify this:

1.Is it normal for OVS to use 80% CPU for high traffic,is there any way to
bring down cpu usage as i am not able to run multiple high traffic vms on
same host,which makes virtualization inefficient.
2.Why there are lot of missed flows and can this be minimized? (From my
understanding missed is because Data path couldn't find flow and need to
contact user daemon to generate one).
3.I have read threads regarding high cpu usage because of too many flows
but in case its under 3000 and still using high cpu,can any one please
clarify this.

Regards,
Ananth
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