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lwIP mirror from http://git.savannah.gnu.org/cgit/lwip.git
ea94549cb2
This makes a couple of simple re-arrangements in lwip_selscan() that
should improve performance in the following ways:
1) The old code linearly walked all sockets to maxfd regardless of
whether they were set in the fd set. The process involved
acquiring sys arch protect, looking up the socket, and then
checking if the socket was present in any of the fd sets. On
systems with lots of sockets and a heavy SYS_ARCH_PROTECT
infrastructure (a mutex) this can result in a lot of extra work.
Now we skip this process for any fd that is not in the input sets
2) If the socket from tryget_socket() is NULL we no longer continue
and compare the input fd sets with a zeroed out set of events
3) We no longer need to zero out our event sets because they are
only accessed when tryget_socket() is successful
lwip_selscan() is called at most once per select call and sometimes up to three times
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| .gitattributes | ||
| .gitignore | ||
| CHANGELOG | ||
| COPYING | ||
| FILES | ||
| README | ||
| UPGRADING | ||
INTRODUCTION
lwIP is a small independent implementation of the TCP/IP protocol
suite that has been developed by Adam Dunkels at the Computer and
Networks Architectures (CNA) lab at the Swedish Institute of Computer
Science (SICS).
The focus of the lwIP TCP/IP implementation is to reduce the RAM usage
while still having a full scale TCP. This making lwIP suitable for use
in embedded systems with tens of kilobytes of free RAM and room for
around 40 kilobytes of code ROM.
FEATURES
* IP (Internet Protocol) including packet forwarding over multiple network
interfaces
* ICMP (Internet Control Message Protocol) for network maintenance and debugging
* IGMP (Internet Group Management Protocol) for multicast traffic management
* UDP (User Datagram Protocol) including experimental UDP-lite extensions
* TCP (Transmission Control Protocol) with congestion control, RTT estimation
and fast recovery/fast retransmit
* Specialized raw/native API for enhanced performance
* Optional Berkeley-like socket API
* DNS (Domain names resolver)
* SNMP (Simple Network Management Protocol)
* DHCP (Dynamic Host Configuration Protocol)
* AUTOIP (for IPv4, conform with RFC 3927)
* PPP (Point-to-Point Protocol)
* ARP (Address Resolution Protocol) for Ethernet
LICENSE
lwIP is freely available under a BSD license.
DEVELOPMENT
lwIP has grown into an excellent TCP/IP stack for embedded devices,
and developers using the stack often submit bug fixes, improvements,
and additions to the stack to further increase its usefulness.
Development of lwIP is hosted on Savannah, a central point for
software development, maintenance and distribution. Everyone can
help improve lwIP by use of Savannah's interface, Git and the
mailing list. A core team of developers will commit changes to the
Git source tree.
The lwIP TCP/IP stack is maintained in the 'lwip' Git module and
contributions (such as platform ports) are in the 'contrib' Git module.
See doc/savannah.txt for details on Git server access for users and
developers.
The current Git trees are web-browsable:
http://git.savannah.gnu.org/cgit/lwip.git
http://git.savannah.gnu.org/cgit/lwip/lwip-contrib.git
Submit patches and bugs via the lwIP project page:
http://savannah.nongnu.org/projects/lwip/
DOCUMENTATION
The original out-dated homepage of lwIP and Adam Dunkels' papers on
lwIP are at the official lwIP home page:
http://www.sics.se/~adam/lwip/
Self documentation of the source code is regularly extracted from the
current Git sources and is available from this web page:
http://www.nongnu.org/lwip/
There is now a constantly growin wiki about lwIP at
http://lwip.wikia.com/wiki/LwIP_Wiki
Also, there are mailing lists you can subscribe at
http://savannah.nongnu.org/mail/?group=lwip
plus searchable archives:
http://lists.nongnu.org/archive/html/lwip-users/
http://lists.nongnu.org/archive/html/lwip-devel/
Reading Adam's papers, the files in docs/, browsing the source code
documentation and browsing the mailing list archives is a good way to
become familiar with the design of lwIP.
Adam Dunkels <adam@sics.se>
Leon Woestenberg <leon.woestenberg@gmx.net>