Messages in this thread |  | | From | (Rob Janssen reading Linux mailinglist) | Subject | Re: More TCP speed fixes | Date | Fri, 17 May 1996 23:21:24 +0200 (MET DST) |
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According to Eric Schenk: > (5) I've made some changes to the way delayed ACKs are treated. > In particular if the packet interarrival time is larger than > 1/2 second, then delaying ACKs is a bad idea, since it will just > result in skewing the RTT calculation for the sender. > So, I changed things so that if sk->ato > HZ/2, we simply don't > delay the ACK at all.
Note that when you implement such fixed time comparisons, you may adversely affect performance in environments that are operating slower than you think is reasonable. Most notably, amateur packet radio (which benefits a lot from any delayed ack scheme) often has packet interarrival times > 1/2 second.
It is better to adjust the time threshold depending on the serial speed and the MTU or MRU. (of course, as I wrote earlier, performance in amateur packet radio will benefit even more from a TCP implementation that knows about halfduplex interfaces and does not queue replies before carrier drops)
Rob
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