Messages in this thread |  | | Date | Sun, 14 Oct 2001 10:05:33 +0300 | From | Mika Liljeberg <> | Subject | Re: TCP acking too fast |
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"David S. Miller" wrote: > > You need to post for us a tcpdump trace of a connection you feel > exhibits bad behavior. > > Otherwise we can do nothing but guess, effectively your statistics > aren't helpful at all if we have no idea what is happening on the > wire.
Fair enough, chalk it down to lack of sleep addling my brain. I also forgot to mention my kernel version, which is 2.4.10-ac10.
I've attached a fragment of tcpdump output from the middle of steady state transfer. Looking at the dump, it seems that most arriving segments have the PSH bit set. This leads me to believe that the transfer is mostly application limited at the sender side.
For some reason, this causes the receiver to ack every segment immediately (which is not suggested by the spec as far as I know). I'm guessing that this is some kind of optimization for HTTP (i.e., avoid Nagle on the last runt segment by acking pushed segments immediately). However, this seems to produce less than desirable behaviour on sender limited bulk transfers.
However, despite appearances, I can't seem to find the bit of code that tests the PSH flag for immediate ack. Still sleepy, I guess.
Regards,
MikaL[unhandled content-type:application/x-gzip] |  |