Hi all, I want to add a new function in openvswitch so that some packets can always be processed by userspace (ofproto) instead of the kernel (datapath).
To implement this, first we want to confirm our understanding of how the openwswitch processes packets. Currently we believe, there are three types of "rules": 1) classifier (lives in userspace), which is the OpenFlow flow table (can contain wildcard rules); 2)facet (also lives in userspace), which only has exact match rules; 3) subfacet (lives in kernel), which only has exact match rules. >From our understanding, when a switch receives a packet, the kernel space will first look up the subfacets currently installed in the kernel. If no match, the kernel will trigger an upcall sending the packet to userspace. Then the userspace will first lookup the facet in handle_flow_miss() via facet_lookup_valid(). If no match, userspace will lookup the classifier via rule_dpif_lookup() and create a facet for the rule from the classifier. After that, handle_flow_miss_with_facet() is called so that the packet is handle by this facet. After the packet is handed to handle_flow_miss_with_facet(), a subfacet will be created from the facet. If there is any error in the above statement, please point that out, or any explanation of the different types of rules would be greatly appreciated. My question about the packet processing in openvswitch is: How is the subfacet installed back to datapath? via which function call in userspace? How this packet is forwarded (processed) by userspace? and via which function call? This two questions confused me since I did not find the related function calls in handle_flow_miss_with_facet(). In handle_flow_miss_with_facet(), struct dpif_execute is created, However, it is never used in the function. I am wondering if this struct is related to the packet processing, and if yes, how does ovs use this struct. Thanks, Xiaoye -- Xiaoye (Steven) Sun, Ph.D. Student Department of Electrical and Computer Engineering (ECE) & Department of Computer Science (CS) George R. Brown School of Engineering Rice University, Houston, Texas, USA
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