[ovs-discuss] No buffer space available warning
blp at nicira.com
Mon Jun 11 17:11:28 UTC 2012
On Mon, Jun 11, 2012 at 06:14:17PM +0500, Junaid Khalid wrote:
> With the following are the platform specifications:
> OVS version: 1.4.0
> traffic type: MTU size UDP packets @7000packets per second, generating
> 50,000 flows by changing UDP src Ports.
> OS: Fedora release 12, Linux 126.96.36.199-127.fc12.i686.PAE
> CPU: Intel Core i3 @ 2100 GHz
> Controller: NOX, simple IP based switching application.
> If I generate 50,000 flows in two chunks, for example, first I generate
> traffic with src Port from 1 to 20,000 for few seconds then change the src
> Port range to 20,001 to 50,000, I get the following warnings:
> Jun 11 16:41:06|00019|dpif|WARN|system at br0: recv failed (No buffer space
> Jun 11 16:41:19|00020|dpif|WARN|system at br0: recv failed (No buffer space
> Jun 11 16:41:22|00021|dpif|WARN|system at br0: recv failed (No buffer space
> Jun 11 16:41:24|00022|dpif|WARN|system at br0: recv failed (No buffer space
> Following is the output of "ovs-dpctl show br0"
> system at br0:
> lookups: hit:491818 missed:603323 lost:116749
> flows: 28559
> Moreover, if I generate 50,000 flows in one go, without any pause, then I
> do not get any error.
> How to diagnose the problem? Has anyone else experienced such problem with
> reactive flow writing?
The problem is that packets are being dropped in the kernel-to-user
buffers. You can try Open vSwitch from the "master" or "branch-1.7"
branches, which should handle this workload much better.
If your controller is receiving the first packet of every UDP flow,
I'm surprised that it can keep up.
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