Difference between revisions of "Cluster:LowLatency"
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(→Low Latency TCP/IP for Linux notes) |
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| − | == | + | ==Plan== |
| + | * Test tcp_low_latency - does it work? If so, what does it do _exactly_ | ||
| + | |||
| + | ==Notes== | ||
*Comparisons & Instrumentation | *Comparisons & Instrumentation | ||
Revision as of 17:41, 28 August 2005
Plan
- Test tcp_low_latency - does it work? If so, what does it do _exactly_
Notes
- Comparisons & Instrumentation
- Comparison of time between layers in network stack. Patch only for 2.6.9.
- Comparing while varying link delay times
- http://developer.osdl.org/shemminger/LK2004_TCP.pdf
- http://developer.osdl.org/shemminger/LWE2005_TCP.pdf
- Reno - Linux 2.4
- Westwood - Wireless
- Vegas
- Binary Increase Congestion Control (BIC) - Default for Linux 2.6
- Comparing while varying link delay times
- Lots of discussion
- http://www.ggf.org/Public_Comment_Docs/Documents/May-2005/draft-ggf-dtrg-survey-1.pdf
- HS-TCP
- Scalable TCP
- FAST TCP
- BIC & CUBIC
- Westwood
- .....
- Lots of discussion
- Misc
- Dynamic Right Sizing (DRS)
- Window Scaling RFC
- Modifying buffer sizes manually
- Kernel options
- Default Linux TCP/IP options field contains:
- Maximum Segment Size(MSS) http://rfc.activedomain.org/0500-0999/rfc0879.html
- Selective Acknowledgement(Sack) ftp://ftp.isi.edu/in-notes/rfc2018.txt
- Timestamping http://www.faqs.org/rfcs/rfc1323.html
- opensolaris code
- Low Latency Kernel Option
- net.ipv4.tcp_low_latency sysctl
- /proc/sys/net/ipv4/tcp_low_latency
- From /usr/src/linux/Documentation/networking/ip-sysctl.txt
- net.ipv4.tcp_low_latency sysctl
tcp_low_latency - BOOLEAN
If set, the TCP stack makes decisions that prefer lower
latency as opposed to higher throughput. By default, this
option is not set meaning that higher throughput is preferred.
An example of an application where this default should be
changed would be a Beowulf compute cluster.
Default: 0
