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

Motonori Shindo motonori at shin.do
Tue Oct 1 08:52:08 UTC 2013


Ananth,

"megaflows" support was added in v1.11.0 so 1.9.3 doesn't have it.

Regards,

---
Motonori Shindo

On 2013/10/01, at 16:37, ananthan <ananthannair935 at gmail.com> wrote:

> Thanks Justin,
>                       For Xenserver i am planning to upgrade from 1.4 to 1.9.Does 1.9.3 have wild carding feature.
> Regards,
> Ananth                     
> 
> 
> On Tue, Oct 1, 2013 at 11:22 AM, Justin Pettit <jpettit at nicira.com> wrote:
> Correct.  Multi-threading is going to be part of the 2.0 release.  The improvement you're seeing is from our adding support for wildcarding in the kernel.  We've been calling it megaflows.  (As opposed to the previous exact-match microflows that were installed.)  In the new model, ovs-vswitchd tries to wildcard as many fields as it can based on the configuration.  Since you are just doing normal switching that matches on L2 addresses, most of the fields are now wildcarded and these megaflows are covering the bulk of your traffic.
> 
> --Justin
> 
> 
> On Sep 30, 2013, at 10:18 PM, ananthan <ananthannair935 at gmail.com> wrote:
> 
> > Hi,
> >      Tested ovs 1.11 on ubuntu 12.04 and recreated above workload,this time i am so shocked to see that Load Average didnt go more than 0.1%  which is nearly 80 times improvement when compared to previous situation :) .It solves all the issue that we were facing with old release,thanks for fixing all those issue.Also i noticed that missed count is also far less.
> >
> > Waiting to upgrade it on xenserver 6.0.2
> >
> > but i dont see ovs-vswitchd threads using much cpu,so i assume its not the multi-threading that fixed this,can you please tell me the most important optimization that made to fix above things.
> >
> > Regards,
> > Ananthan
> >
> >
> >
> >
> > On Tue, May 28, 2013 at 9:12 PM, Justin Pettit <jpettit at nicira.com> wrote:
> >
> > On May 28, 2013, at 8:39 AM, ananthan <ananthannair935 at gmail.com> wrote:
> >
> > > Hi,
> > >      this is the only output for
> > >
> > > ovs-ofctl dump-flows xapi3
> > >
> > > duration=5120780.012s, table=0, n_packets=48344340859, n_bytes=12069667659298, priority=0 actions=NORMAL
> > >
> > >     when i discussed this question on IRC someone pointed about :
> > >
> > > above default flow makes  ovs a standard learning/forwarding L2 switch.
> > >
> > > Does this point has any part in high cpu usage?
> >
> > No.
> >
> > --Justin
> >
> >
> >
> 
> 
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---
Motonori Shindo







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