[ovs-dev] [PATCH v4 0/3] Use improved dp_hash select group by default

[Ben Pfaff]

On Thu, May 24, 2018 at 05:27:58PM +0200, Jan Scheurich wrote:
> The current default OpenFlow select group implementation sends every new L4 flow
> to the slow path for the balancing decision and installs a 5-tuple "miniflow"
> in the datapath to forward subsequent packets of the connection accordingly. 
> Clearly this has major scalability issues with many parallel L4 flows and high
> connection setup rates.
> 
> The dp_hash selection method for the OpenFlow select group was added to OVS
> as an alternative. It avoids the scalability issues for the price of an 
> additional recirculation in the datapath. The dp_hash method is only available
> to OF1.5 SDN controllers speaking the Netronome Group Mod extension to 
> configure the selection mechanism. This severely limited the applicability of
> the dp_hash select group in the past.
> 
> Furthermore, testing revealed that the implemented dp_hash selection often
> generated a very uneven distribution of flows over group buckets and didn't 
> consider bucket weights at all.
> 
> The present patch set in a first step improves the dp_hash selection method to
> much more accurately distribute flows over weighted group buckets and to
> apply a symmetric dp_hash function to maintain the symmetry property of the
> legacy hash function. In a second step it makes the improved dp_hash method
> the default in OVS for select groups that can be accurately handled by dp_hash.
> That should be the vast majority of cases. Otherwise we fall back to the
> legacy slow-path selection method.
> 
> The Netronome extension can still be used to override the default decision and
> require the legacy slow-path or the dp_hash selection method.

Thanks a lot.  I applied this series to master.