In　modern　data　center　networks　(DCNs),　network-stack　processing　denotes　a　large　portion　of　the　end-to-end　latency　of　TCP　flows.　So　profiling　network-stack　latency　anomalies　has　been　considered　as　a　crucial　part　in　DCN　performance　diagnosis　and　troubleshooting.　In　particular,　such　profiling　requires　full　coverage　(i.e.,　profiling　every　TCP　packet)　and　low　overhead　(i.e.,　profiling　should　avoid　high　CPU　consumption　in　end-hosts).　However,　existing　solutions　rely　on　system　calls　or　tracepoints　in　end-hosts　to　implement　network-stack　latency　profiling,　leading　to　either　low　coverage　or　high　overhead.　We　propose　Torp,　a　framework　that　offers　full-coverage　and　low-overhead　profiling　of　network-stack　latency.　Our　key　idea　is　to　offload　as　much　of　the　profiling　from　costly　system　calls　or　tracepoints　to　the　Torp　agent　built　on　eBPF　modules,　and　further　to　include　a　Torp　handler　on　the　ToR　switch　to　accelerate　the　remaining　profiling　operations.　Torp　efficiently　coordinates　the　ToR　switch　and　the　Torp　agent　on　end-hosts　to　jointly　execute　the　entire　latency　profiling　task.　We　have　implemented　Torp　on　$32\times　100$　Gbps　Tofino　switches.　Testbed　experiments　indicate　that　Torp　achieves　full　coverage　and　orders　of　magnitude　lower　host-side　overhead　compared　to　other　solutions.