Network Level Framing in INSTANCE

1
Network Level Framing in INSTANCE
Pål Halvorsen, Thomas Plagemann, and Vera
Goebel University of Oslo, UniK- Center for
Technology at Kjeller Norway

• Overview
• Application Scenario
• The INSTANCE project
• Zero-Copy-One-Copy Memory Architecture
• Integrated Error Management
• Network Level Framing
• Conclusions

2
Application Scenario
Media-on-Demand server Applicable in
applications like News- or Video-on-Demand
provided by city-wide cable or pay-per-view
companies
Multimedia Storage Server
Network
Network

• Retrieval is the bottleneckSome important
  factors
• Memory management
• Error management
• Communication protocol processing

• Project goalsOptimize performance within a
  single server
• Reduce resource requirements
• Maximize number of clients

3
Zero-Copy-One-Copy I
4
Zero-Copy-One-Copy II
Zero-Copy
Delay-Minimized Broadcast
5
Traditional Error Management
6
Integrated Error Management
7
Traditional Storage
Upload to server Frequency low (1)
Download from server Frequency very high
8
Network Level Framing (NLF)
9
NLFWhen to Store Packets
10
NLFSplitting the UDP Protocol
11
NLFChecksum Operations I

• The UDP checksum covers three fields
• A 12 byte pseudo header containg fields from the
  IP header
• The 8 byte UDP header
• The UDP data
• Checksum calculation function (in_cksum)

u_16int_t w for each mbuf in packet w
mbuf-gtm_data while data in mbuf checksum
w w
12
NLFChecksum Operations II

• Traditional checksum operation

13
NLFChecksum Operations III

• NLF checksum operation

14
Integrated Error Management and NLF
Network
15
Expected Performance Gain

• Traditionally, 60 of the UDP/IP processing is
  spent on checksum calculation Kay et al. 93
• Performance gain using NLF (packet size
  dependent)
• The checksum operation is greatly reduced
• E.g., 4KB packet size ? checksum operation on
  only 0.2 of data
• Speed-up factor of about 2
• Throughput gain of about 10

16
Conclusion

• The INSTANCE project aims at optimizing the
  data retrieval in an MoD server
• Zero-Copy-One-Copy memory architecture
• Integrated Error Management
• Network Level Framing
• Saving time for checksum calculation where
  expected performance gain is
• About 99 reduction of the checksum calculation
  time (UDP/IP processing speed-up of 2)
• About 10 increase in throughput
• Future work