[ovs-dev] [PATCH v2] datapath: Remove tunnel header caching.

Ben Pfaff blp at nicira.com
Fri Oct 26 18:21:24 UTC 2012


On Fri, Oct 26, 2012 at 11:19:37AM -0700, Ben Pfaff wrote:
> On Thu, Oct 25, 2012 at 11:14:38AM -0700, Pravin B Shelar wrote:
> > v1-v2:
> > 	- Fixed capwap fragment case.
> > 	- simplified tnl_send.
> > --8<--------------------------cut here-------------------------->8--
> > 
> > Tunnel caching was added to reduce CPU utilization on TX path
> > by caching packet header, So performance gain is directly proportional
> > to number of skbs transferred. But with help of offloads skb are getting
> > larger. So there are less number of skbs. Therefore header caching does
> > not shows similar gains we seen in past. And now kernel 3.6 has removed
> > dst caching from networking which makes header caching even more tricky.
> > So this commit removes header caching from OVS tunnelling.
> > 
> > Signed-off-by: Pravin B Shelar <pshelar at nicira.com>
> 
> Is there any benefit in adding a comment to tunnel.h remarking that
> the bit 1<<6 is reserved because it was previously used?  (Maybe not,
> if we're deleting this interface entirely in another version.)

Oh, and in netdev-vport.c, should we silently ignore the header_cache
option instead of warning that it's unknown?  Or instead warn that
it's not useful anymore?



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