On Thu, Apr 12, 2018 at 01:01:09PM +0000, Gabor Halász wrote: > In real-world vSwitch deployments, handling a few thousand flows, > EMC is quickly saturated, so it's optimal usage is critical to > reach the highest packet forwarding speed of the vSwitch. > > EMC lookup is initiated based on the hash value of the packet. > In case the packet does not already have a stored hash value > during processing, the miniflow_hash_5tuple() function is invoked > in the datapath. While packets entering the vSwitch from an > external interface usually have valid hashes (pre-computed by NICs > supporting RSS), the ones coming from vhostuser ports (internal > packets from VMs) do not. > > Non-IP traffic received from the VMs experiences very bad EMC hit > rates and hence forwarding performance, because the miniflow_hash_5tuple() > returns the same hash value and these packets will hit the same EMC > entries and cause collisions if there are more than two distinct > megaflows with traffic in the PMD. > > The purpose of the patch is to compute proper hashes with sufficient > entropy for EMC lookup also for non-IP traffic to avoid constant EMC > thrashing. The hash calculation has been extended to handle unrecognized > ethernet types and MPLS, using the header fields that are valid for a > specific protocol. > > Forwarding of non-IP packets in NFVI scenarios is very likely to happen > based on MAC addresses and/or VLAN tags. > By implementing a special case for matching on MPLS label, this change > prepares a separate commit that will enable hash recalculation for MPLS > packets received from L3 GRE tunnels. Today we skip re-computation of > the hash and the original GRE hash is only updated with the increased > recirc_depth. > > Signed-off-by: Gabor Halasz <gabor.hal...@ericsson.com> > --- > v1->v2: > - Fix for Clang error "cast increases required alignment from 2 to 4"
Thanks for v2. It doesn't make a difference because OVS_FORCE does not affect Clang, only sparse. _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev