In　network　function　virtualization　(NFV),　network　functions　(NFs)　are　chained　as　a　service　function　chain　(SFC)　to　enhance　NF　management　with　high　flexibility.　Recent　solutions　indicate　that　the　processing　performance　of　SFCs　can　be　significantly　improved　by　offloading　NFs　to　programmable　switches.　However,　such　offloading　requires　a　deep　understanding　of　NF　properties　to　achieve　the　maximum　SFC　performance,　which　brings　non-trivial　burdens　to　network　administrators.　In　this　paper,　we　propose　LightNF,　a　novel　system　that　simplifies　NF　offloading　in　programmable　networks.　LightNF　automatically　dissects　comprehensive　NF　properties　(e.g.,　NF　performance　behaviors)　via　code　analysis　and　performance　profiling　while　eliminating　manual　efforts.　It　then　leverages　the　analyzed　NF　properties　in　its　SFC　placement　so　as　to　produce　the　performance-optimal　offloading.　We　have　implemented　a　LightNF　prototype.　Our　experiments　show　that　LightNF　outperforms　state-of-the-art　solutions　with　an　orders-of-magnitude　reduction　in　per-packet　processing　latency　and　9.5x　improvement　in　SFC　throughput.