Performance challenges in software networking
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SDN performance issues and how to overcome them
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Performance challenges in software networking
- 1. Performance Challenges In Software Networking Stephen Hemminger @networkplumber
- 2. Who am I? ● Principal Architect Brocade vRouter (Vyatta) ● Fellow Linux Foundation ● Sequent Unix SMP networking ● DPDK – #3 contributor ● Linux – 10+ year contributor – Maintainer ● Bridge ● iproute
- 3. Agenda ● Myths ● Requirements ● Benchmarks ● Reality
- 4. Myths ● Software networking can never do: – 1Gbit ● 2008 – Linux, FreeBSD, ... – 10Gbit ● 2013 – DPDK, Netmap, ... – 40Gbit ● 2015 – DPDK, ... – 100Gbit ● 2016?
- 5. Hardware vs Software ● Clock rate ● TCAM size ● TCAM miss ● Bus transactions ● Clock rate ● Cache size ● Cache misses per packet ● PCI bus operations
- 7. SDN Measurement Forwarding RFC2544 Scaling Imix, BGP, Firewall, ... Application BGP convergence Availablity SDN Workload Performance Test Environment
- 8. Benchmark vs Reality ● Benchmark – random flows – 10 or less rules – 128GB memory – 32 or more CPU ● Reality – Burstyflows – 1000's of rules – 2GB VM – 2-4 CPU
- 9. System effects ● Data/Control resource sharing – CPU cache – Background noise ● Power consumption ● Memory footprint ● Virtualization overhead ● Platform differences
- 10. Basics memory is ~70+ ns away (i.e. 2.0 GHz = 140+ cycles) Source: Intel® 64 and IA-32 Architectures: Optimization Reference Manual Sandy Bridge Ivy Bridge Haswell Skylake (bytes/cycle) 4 4 4 L1 Peak Bandwidth 2x16 2x32 load 1x32 store 2x32 load 1x32 store L2 data access (cycles) 12 11 12 L2 peak Bandwidth 1x32 64 64 Shared L3 access (cycles) 26-31 34 44 L3 peak bandwidth 32 - 32 Data hit in L2 cache 43 – clean hit 60 – modified
- 11. Time Budget ● 10Gbit 64 byte packet – 67.2ns = 201 cycles @ 3Ghz ● Cache – L3 = 8 ns – L2 = 4.3 ● Atomic operations – Lock = 8.25 ns – Lock/Unlock = 16.1 Network stack challenges at increasing speeds – LCA 2015 Jesper Dangaard Brouer
- 12. Magic Exlir?
- 13. Fast vs Slow ● New software – Lockless – Single function – Tight layering – Cache aware ● Legacy software – Interrupts – Shared resources – System calls – VM exit
- 14. Performance Tradeoffs ● Bulk operations ● Lock-less Algorithms ● Tight integration ● Polling ● Caching ➔ Latency ➔ Update speed Consistency ➔ Inflexible ➔ CPU utilization Power management ➔ Memory utilization Update overhead
- 15. CPU pipeline
- 16. Cache flow Rx Device Network Function Tx Device Rx Poll Tx Kick Tx Descriptor Rx Descriptor Function Table Accesses Worst case 7+ cache miss per packet! Packet Data
- 17. Cache Ping/Pong ● Cache line shared between cores – Statistics – Session state
- 19. Packet batching
- 20. New developments ● DPDK – Multi-architecture – NIC support – Packet pipeline – ACL – LPM – ... ● Linux – Batched Tx – Lockless queue disciplines – Memory allocator performance
- 21. Conclusions ● Software networking is function of: – Algorithims – Low level CPU utilization – Cache behavior
- 22. Questions?
- 24. Next Generation Software Networking ● Openvswitch + DPDK ● Brocade – vRouter ● 6Wind ● FD.io – VPP ● Juniper - Opencontrail ● Huawei - Fusionsphere
- 25. Performance Challenges In Software Networking Stephen Hemminger @networkplumber
- 26. Who am I? ● Principal Architect Brocade vRouter (Vyatta) ● Fellow Linux Foundation ● Sequent Unix SMP networking ● DPDK – #3 contributor ● Linux – 10+ year contributor – Maintainer ● Bridge ● iproute
- 27. Agenda ● Myths ● Requirements ● Benchmarks ● Reality
- 28. Myths ● Software networking can never do: – 1Gbit ● 2008 – Linux, FreeBSD, ... – 10Gbit ● 2013 – DPDK, Netmap, ... – 40Gbit ● 2015 – DPDK, ... – 100Gbit ● 2016?
- 29. Hardware vs Software ● Clock rate ● TCAM size ● TCAM miss ● Bus transactions ● Clock rate ● Cache size ● Cache misses per packet ● PCI bus operations
- 31. SDN Measurement Forwarding RFC2544 Scaling Imix, BGP, Firewall, ... Application BGP convergence Availablity SDN Workload Performance Test Environment
- 32. Benchmark vs Reality ● Benchmark – random flows – 10 or less rules – 128GB memory – 32 or more CPU ● Reality – Burstyflows – 1000's of rules – 2GB VM – 2-4 CPU
- 33. System effects ● Data/Control resource sharing – CPU cache – Background noise ● Power consumption ● Memory footprint ● Virtualization overhead ● Platform differences
- 34. Basics memory is ~70+ ns away (i.e. 2.0 GHz = 140+ cycles) Source: Intel® 64 and IA-32 Architectures: Optimization Reference Manual Sandy Bridge Ivy Bridge Haswell Skylake (bytes/cycle) 4 4 4 L1 Peak Bandwidth 2x16 2x32 load 1x32 store 2x32 load 1x32 store L2 data access (cycles) 12 11 12 L2 peak Bandwidth 1x32 64 64 Shared L3 access (cycles) 26-31 34 44 L3 peak bandwidth 32 - 32 Data hit in L2 cache 43 – clean hit 60 – modified
- 35. Time Budget ● 10Gbit 64 byte packet – 67.2ns = 201 cycles @ 3Ghz ● Cache – L3 = 8 ns – L2 = 4.3 ● Atomic operations – Lock = 8.25 ns – Lock/Unlock = 16.1 Network stack challenges at increasing speeds – LCA 2015 Jesper Dangaard Brouer
- 36. Magic Exlir?
- 37. Fast vs Slow ● New software – Lockless – Single function – Tight layering – Cache aware ● Legacy software – Interrupts – Shared resources – System calls – VM exit
- 38. Performance Tradeoffs ● Bulk operations ● Lock-less Algorithms ● Tight integration ● Polling ● Caching ➔ Latency ➔ Update speed Consistency ➔ Inflexible ➔ CPU utilization Power management ➔ Memory utilization Update overhead
- 39. CPU pipeline
- 40. Cache flow Rx Device Network Function Tx Device Rx Poll Tx Kick Tx Descriptor Rx Descriptor Function Table Accesses Worst case 7+ cache miss per packet! Packet Data
- 41. Cache Ping/Pong ● Cache line shared between cores – Statistics – Session state
- 43. Packet batching
- 44. New developments ● DPDK – Multi-architecture – NIC support – Packet pipeline – ACL – LPM – ... ● Linux – Batched Tx – Lockless queue disciplines – Memory allocator performance
- 45. Conclusions ● Software networking is function of: – Algorithims – Low level CPU utilization – Cache behavior
- 46. Questions?
- 48. Next Generation Software Networking ● Openvswitch + DPDK ● Brocade – vRouter ● 6Wind ● FD.io – VPP ● Juniper - Opencontrail ● Huawei - Fusionsphere