[ovs-dev] xlate_select_group() not being invoked for every packet

Ben Pfaff blp at nicira.com
Tue Feb 18 22:37:59 UTC 2014


It tells the caching code that every packet in the flow in question must
go to the userspace "slow path".  The "controller" keyword ordinarily
would mean that packets have to go to the controller, but that reason is
only there for humans to read in "ovs-dpctl" flow dumps and doesn't
actually cause anything to be sent to the controller.  In a real patch I
would add a new SLOW_* constant for this purpose.

On Tue, Feb 18, 2014 at 02:08:58PM -0700, Mohammad Ali Salahuddin wrote:
> Adding ctx->xout->slow |= SLOW_CONTROLLER; to xlate_select_group()
> resolved my issue. Thank you *very* much.
> 
> So, does this statement completely shut off caching? How does it work
> under the hood? I am curious because intuitively "SLOW_CONTROLLER"
> would mean more caching should be performed at the switch (as the
> connection with the controller is slow). However, it seems to be
> working in the opposite way.
> 
> Any insight into this would be really appreciated.
> 
> Thanks!! 
> > Date: Tue, 18 Feb 2014 09:37:21 -0800
> > From: blp at nicira.com
> > To: saeenali at hotmail.com
> > CC: dev at openvswitch.org
> > Subject: Re: [ovs-dev] xlate_select_group() not being invoked for every packet
> > 
> > You can add
> >     ctx->xout->slow |= SLOW_CONTROLLER;
> > to xlate_select_group().
> > 
> > On Tue, Feb 18, 2014 at 09:46:03AM -0700, Mohammad Ali Salahuddin wrote:
> > > Is there a way to turn off this caching?
> > > Thanks!
> > > 
> > > > Date: Tue, 18 Feb 2014 08:32:54 -0800
> > > > Subject: Re: xlate_select_group() not being invoked for every packet
> > > > From: blp at nicira.com
> > > > To: saeenali at hotmail.com
> > > > CC: dev at openvswitch.org
> > > > 
> > > > On Tue, Feb 18, 2014 at 7:31 AM, Mohammad Ali Salahuddin
> > > > <saeenali at hotmail.com> wrote:
> > > > > Then, I started to a log a message whenever this function was invoked. To my
> > > > > surprise, the logging revealed that this function is not being invoked for
> > > > > every packet.
> > > > >
> > > > > Is this the expected behavior? Am I missing something?
> > > > 
> > > > Open vSwitch caches forwarding choices for performance.
> > >  		 	   		  
> > 
> > > _______________________________________________
> > > dev mailing list
> > > dev at openvswitch.org
> > > http://openvswitch.org/mailman/listinfo/dev
> > 
>  		 	   		  

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