Kieran Mansley yazmış:
On Wed, 2006-10-11 at 16:25 +0300, Çağlar AKYÜZ wrote:
Actually I think this will not improve the performance of MAC. Because
ACK'ing of TCP frames is one of the major drawbacks which degrades
performance ( thanks to Delayed ACK algorithm!).
Only in a very limited set of circumstances will the delayed ACK
algorithm result in poorer performance. Namely, when the TCP window has
been set to a very small value. Changing this configuration option will
remove any bottleneck that the delayed ACK algorithm is imposing.
I tried to increase recieve window but it always resulted in a poorer
performance with my SAM7X. ( Maybe I'm too low in memory?) . is TCP
window size related to somewhat pbufs? I don't know if I have to
increase number of buffers as well.
There
are TCP extensions such as the "quickack" mode in linux's TCP stack that
stop the use of delayed ACK during the slow start phase of TCP
connections, but the performance difference that this is likely to lead
to in lwIP is minimal.
Actually I didn't mean to say that problem is related to LWiP. I wanted
to say that delayed ACK algorithm is slowing TCP connections in our case
and my Windows machine do not provide me any way to change this setting.
( Thanks to Linux as you noted. )
ACKing of packets can be arguably said in fact to increase performance,
as without it the sender couldn't discover the maximum rate it could
send without packet loss, and so if it didn't wish to lose data would
have to be more conservative with how fast it sent packets.
Thanks for this quote. I'll remember this.
Çağlar
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