Messages in this thread | | | Date | Sat, 21 Mar 1998 00:06:10 -0800 | From | "David S. Miller" <> | Subject | Re: TCP fix for sluggish rlogin/rsh |
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Date: Fri, 20 Mar 1998 16:25:40 +0100 (CET) From: Andrea Arcangeli <arcangeli@mbox.queen.it>
On Wed, 18 Mar 1998, David S. Miller wrote:
>This is the right fix. It should apply cleanly to 2.1.90, but >even if it doesn't you can get the idea. We ACK quickly, if we >see PSH _and_ we saw less than 1/2 the MSS worth of data in >incoming packet.
Seems to work well against 2.1.90 even if 2.0.33 seems again a __bit__ faster. I don' t know what "tp->ato = HZ/50" means but maybe setting it to a lower value.... but I havn' t tried yet since I don't know if it make sense.
tp->ato is the period for which we delay a delayed ACK. I cannot set it lower for two reasons:
1) The next nice multiple value lower is HZ/100, this has a special meaning, as it forces out an immediate ACK.
2) Delaying too quickly prevents NAGLE from being realized, enough time must pass so that the application can have a chance to read the data, and send the echo characters back, on which the ACK can be "piggybacked". This saves bandwidth on the network.
I'm sure there are a few quirks with my current scheme. If people believe the current heuristic acts suboptimally in certain cases, or when talking to some other TCP implementations, _please_ send me packet traces of the behavior in progress. I can only analyze and fix the behavior when I have this information.
Later, David S. Miller davem@dm.cobaltmicro.com
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