a look at intel's dataplane development kit
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A Look at Intel’s Dataplane Development Kit
Dominik Scholz
Chair for Network Architectures and Services
Department for Computer ScienceTechnische Universitat Munchen
June 13, 2014
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 1
Outline
1 Packet Processing using Commodity Hardware
2 Intel’s Dataplane Development Kit
3 Comparison: Intel’s DPDK, netmap, PF RING DNA
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 2
Motivation
Why use commodity hardware and do packet processing insoftware?
Advantages:Flexibility: software can be modifiedIncreased performance and reduced costs of(multicore) CPU’s and NIC’s over the last yearsOpen source
But: existing dataplane software not designed for high-speedpacket processing (up to 10 Gbit/s)→ specialized frameworks implement different techniques toachieve significant performance speed-ups
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 3
Use Case: Linux Network Stack
Ingress Network Board Egress Network BoardMemory
Operating System
Buffer Buffer
1
9
Routing Table
2
3
4 5
78
10
11
Kernel Mode
User ModeApplikation
6
7
Applikation
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 4
Performance Limitating Factors
Bottleneck CPUBottleneck memory:
1 per packet allocation and deallocation2 multiple copy operations per packet3 complex sk buff structure
Parallelism: spinlocks (active waiting)Context switches
Conclusion: standard dataplane only for general purpose
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 5
Performance Limitating Factors
Bottleneck CPUBottleneck memory:
1 per packet allocation and deallocation2 multiple copy operations per packet3 complex sk buff structure
Parallelism: spinlocks (active waiting)Context switches
Conclusion: standard dataplane only for general purposeDominik Scholz: A Look at Intel’s Dataplane Development Kit 5
Performance Limitating Factors
Bottleneck CPUBottleneck memory:
1 per packet allocation and deallocation2 multiple copy operations per packet3 complex sk buff structure
Parallelism: spinlocks (active waiting)Context switches
Conclusion: standard dataplane only for general purpose
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 5
Outline
1 Packet Processing using Commodity Hardware
2 Intel’s Dataplane Development Kit
3 Comparison: Intel’s DPDK, netmap, PF RING DNA
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 6
Intel DPDK
Set of libraries to accelerate basic dataplane functionsReleased in 2012Completely replaces the network stackIntel architecture-based: supporting Intel Atom - Intel XeonOpen SourceBSD-licensed: free and unsupported standalone orcommercial solution
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 7
DPDK Overview
Runtime environment with lowoverhead
Dataplane libraries run inuserspace
1 Memory management2 Buffer management3 Custom driver4 ...
Environment AbstractionLayer (EAL)
”Easy to use.” - Intel
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 8
Queue Manager
Fixed-sized ring implemented as table of pointer to any object
Properties:FIFOLockless (no active waiting)Supports multi consumer/producer enqueue/dequeuescenariosSupports bunch-processing of objects
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 9
Memory Manager
mempool structure:Pool of fixed-sized objectsUses a ring to store free objectsPer core cache (optional)
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 10
Buffer Manager
mbuf structure used to store network packetsCreated before runtime”Allocation”: take a free mbuf from a mempool”Deallocation”: put the mbuf back to the mempoolSmall size to fit in one cache-line (→ mbuf-chaining)
mbuf contains:1 Metadata: control information, e.g. packet length2 Pointer to next mbuf3 Packet data: header and payload
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 11
How to use the DPDK - EAL
The DPDK creates libraries by creating the EAL:Hides environment specificsProvides standard programming interfaceOptimized for the available hardware
But does not provide:Layer-3 forwardingFirewalls...any layer 3 or upper protocol
→Developer has to port his application to the DPDK
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 12
Outline
1 Packet Processing using Commodity Hardware
2 Intel’s Dataplane Development Kit
3 Comparison: Intel’s DPDK, netmap, PF RING DNA
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 13
netmap
A framework for raw packet I/O, developed by Luigi Rizzo(Universita di Pisa)
Feature: works with broad range of soft- and hardware
Linux and FreeBSDIntel 10GbE and 1GbE adapterIntel, RealTek, nVidia
Implemented techniques:Memory pre-allocation and re-useMemory mappingBatch processingParallel direct paths (assign CPU core to receiving queue)
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 14
PF RING Direct NIC Access
A framework to capture packets, developed by ntop.
Feature: zero-copyPF RING DNA maps NIC memory and registers to userland→ only one copy operation per packetBut: weakness to user misbehaviour (system-crashes)
Implemented techniques:Memory pre-allocation and re-useMemory mapping (zero-copy)Parallel direct paths
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 15
Summary
Intel DPDK netmap PF RING DNAMemory Pre-allocation 3 3 3
Memory Mapping 3 3 3
Batch Processing 3 3 7
Parallel Direct Paths 3 3 3
Open Source 3 3 3
”Safety” 3 3 7
Test results show:different frameworks exceed in different use cases [2][4]up to 10 times faster than the linux network stack
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 16
Sources
Intel DPDKProgrammers Guide.January 2014.
Intel DPDKPacket Processing on Intel Architecture.Presentation slides, 2012.
Luigi Rizzonetmap: a novel framework for fast packet I/Oin: Proceedings of the 2012 USENIX Annual Technical Conference,2012.
Jose Luis Garcıa-Dorado et al.High-Performance Network Traffic Processing Systems UsingCommodity Hardwarein: Data Traffic Monitoring and Analysis, Springer Verlag, 2013.
www.dpdk.orgLast visited: 06.06.2014
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 17
Thank you for your attention!Do you have any questions?
Dominik Scholz: A Look at Intel’s Dataplane Development Kit 18
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