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eBPF & Switch Abstractions
The document presents a proposal for a fully flexible datapath for a multihost NIC, leveraging technologies like switchdev, qdisc offload, cls_bpf, and XDP. Key steps in implementation are outlined including initialization and qdisc setup, with ongoing work focused on extending functionality and upstreaming enhancements. The presentation highlights collaborative efforts and invites further discussion on the advancements made in networking architecture.
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eBPF & Switch Abstractions
- 1. ©"2018"NETRONOME"SYSTEMS,"INC. 1 eBPF &Switch Abstractions Nick Viljoen <nick.viljoen@netronome.com> Networking Track Vancouver, 14 November 2018
- 2. ©"2018"NETRONOME"SYSTEMS,"INC. 2 Contents ○ Background ○The"MultiCHost"NIC"Abstraction ○ The"Switchdev"Based"MultiCHost"NIC"Abstraction ○ Currently"upstream"(as"of"2"weeks"ago) ○ Boot ○ Setting"Switchdev"Mode ○ Loading"Qdiscs ○ Next"Steps"(currently"being"upstreamed) ○ Generalising Qdisc Offload ○ Adding"clsact"Qdiscs"(u32,"cls_bpf) ○ Future"Work
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- 4. ©"2018"NETRONOME"SYSTEMS,"INC. 4 Background:"HW ○ Many"core,"fully"programmable"network"processor ○48K96"preprocessing"cores ○ 54K120"programmable"cores,"8"threads"per"core,"MIMT ○ up"to"4"PCIe ○ Up to 40"ports"supported ○ ~17MB"of"on"chip"memory ○ 2K24GB of DRAM ○ Distributed"&"Transactional"memory architecture ○ Low"power ○ ~"10K35W"(dependent"on"chip"+"frequency)
- 5. ©"2018"NETRONOME"SYSTEMS,"INC. 5 Background:"HW"Datapath Pre processing Accelerators IMU/EMU PCIe PCIe PCIe PhyPorts Reorder PCIe PCIe PCIe Phy Ports CLSCTM C P LU AT Processing*Islands =*Flow*Processing*Core*(FPC)
- 6. ©"2018"NETRONOME"SYSTEMS,"INC. 6 Background:"eBPF"Offload"Architecture ○ Program"is"written"in"standard"manner ○LLVM"compiled"as"normal ○ The"nfp’s"jit"is"called"like"any"other" architectures"jit" ○ This"converts"the"BPF"bytecode"to"NFP" machine"code ○ Translation"reuses"the"verifier" infrastructure"in"kernel ○ Defining the FPC datapath code using BPF bpf_prog.c LLVM bpf_prog.c Verifier Host"JIT NFP"JIT NFPHost"CPU
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- 13. ©"2018"NETRONOME"SYSTEMS,"INC. 13 3"Key"Steps ○ Initialisation"(.probe) ○App"Initialisation ○ vNIC"Allocation ○ Entering"Switchdev"Mode"(.devlink_eswitch_set) ○ Spawning"Representors ○ Qdisc"Setup"(.ndo_tc_setup) ○ Attaching"Qdisc"to"struct"nfp_abm_link
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- 15. ©"2018"NETRONOME"SYSTEMS,"INC. 15 Devlink Devlink(dev(eswitch(show devlink dev(eswitch(set devlinksb(pool(show devlink sb(pool(set devlink.c nfp_devlink.c nfp_shared_buf.c nfp_app.c ctrl.c nfp_app_eswitch_mode_get() nfp_app_eswitch_mode_set() nfp_shared_buf_pool_get() nfp_shared_buf_pool_set() nfp_mbox_cmd() nfp_mbox_cmd() app=>type=>eswitch_mode_get() app=>type=>eswitch_mode_set() nfp_abm_ctrl_qm_enable struct"nfp_abm struct"nfp_abm_link nfp_abm_eswitch_mode_get nfp_abm_spawn_repr struct"nfp_repr eswitch_mode_get eswitch_mode_set sb_pool_get sb_pool_set struct"nfp_abm_link main.c Entering"Switchdev"Mode Driver Kernel App" Abstraction User"Space
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- 18. ©"2018"NETRONOME"SYSTEMS,"INC. 18 Items"Covered ○ Generalising"Qdisc"Offload ○Structure"changes ○ nfp_abm_link ○ nfp_qdisc ○ The"clsact"Qdisc ○ Motivation ○ Architecture
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- 24. ©"2018"NETRONOME"SYSTEMS,"INC. 24 Items"Covered ○ Firmware"and"BPF"JIT ○Flow"Processing"Core"Datapath ○ cls_bpf"and"Switchdev ○ Architecture ○ XDP"for"Multihost"Systems ○ Problems ○ Proposed"Abstraction
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- 27. ©"2018"NETRONOME"SYSTEMS,"INC. 27 XDP"on"Multi=Host"systems ○ Challenges"that"have"to"be"solved ○XDP"is"an"RX"exclusive"hook ○ Heterogenous"architecture"support"is"nascent ○ Security ○ However"more"and"more"of"the"potential"problems"are"falling"away ○ e.g"David"Ahern’s"recent"work"on"exposing"the"FIB"table
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- 29. ©"2018"NETRONOME"SYSTEMS,"INC. 29 Summary ○ Proposing"a"fully"flexible"datapath"for"a"multiHhost"NIC ○Achieved"through"a"combination"of"switchdev,"qdisc"offload,"cls_bpf"and"XDP ○ Work"in"progress ○ Switchdev"architecture"and"qdisc"offload"has"been"upstreamed ○ Next"is"simple"clsact"support ○ Followed"by"cls_bpf"&"XDP ○ Provides"potential"for"BPF"defined"pipelines"in"heterogenous"architectures ○ See"Jakub’s"talk"at"the"microconference"for"more!
- 30. ©"2018"NETRONOME"SYSTEMS,"INC. 30 Credit"(Team) ○ Jakub"Kicinski ○Jiong"Wang ○ Quentin"Monnet ○ David Beckett ○ Edwin"Peer ○ Johan Moraal ○ Mary Pham
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