On Wednesday 29 April 2009 22:39:45 Bo Han wrote: > What I said was when MRR is not enabled, b43 will always use 1 Mbps as > fallback rate, which will significantly reduce the throughput for some > cases.
No it won't. Fallbacks will only be used if the main rate wasn't correctly adjusted by the RC. That will only happen while it's scaling/probing the rates. If the RC correctly adjusted the rate to your network, only a very tiny number of packets will be retried. (Real world numbers are an average of 1.01-1.02 tries per packet). > For a channel with good quality, 54 Mbps may be the best > throughput bit rate. After two retries fail with 54 Mbps, the bit > rate will drop to 1 Mbps. But in fact, 48 or 36 Mbps may work well as > fallback rate... No they won't. Starting with 54M as fallback is absolutely horrible and it will cause horrible stalls. It will cause packets to be completely lost that otherwise will get through on the second attempt with 1M. That will trigger retries and delays on the upper layers, such as TCP. The TCP frame loss mechanism will kick in, which will just reduce throughput even more. The fact that high rates don't work at all on some b43 devices only helps this fact. -- Greetings, Michael. _______________________________________________ Bcm43xx-dev mailing list [email protected] https://lists.berlios.de/mailman/listinfo/bcm43xx-dev
