Messages in this thread |  | | Date | Sun, 14 Oct 2001 22:32:00 +0300 | From | Mika Liljeberg <> | Subject | Re: TCP acking too fast |
| |
kuznet@ms2.inr.ac.ru wrote: > > Hello! > > > > But sending ACK on buffer drain at least for short > > > packets is real demand, which cannot be relaxed. > > > > Why? This one has me stumped. > > To remove sick delays with nagling transfers (1) and to remove > deadlocks due to starvation on rcvbuf (2) at receiver and on sndbuf > at sender (3). > > Actually, (2) is solved nowadays with compressing queue. (3) can be solved > acking each other segment. But (1) remains. > > Actually, any alternative idea how to solve this could be very useful.
And why (1) is a problem is precisely what I don't understand. Nagle is *supposed* to prevent you from sending multiple remnants. If you don't like it, you disable it in the sender! However:
The only awkward Nagle-related delay I know of appears with e.g. HTTP, when the last undersized segment cannot be sent before everything else is acked. This can be solved using an idea from Greg Minshall, which I thought was quite cool.
The normal Nagle rule goes:
- You cannot send a remnant if there are any unacknowledged segments outstanding
Minshall's version goes:
- You cannot send a remnant if there is already one unacknowledged remnant outstanding
This fixes the trailing remnant problem with HTTP and similar request-reply protocols, while adherring to the spirit of Nagle. There was even an I-D at some point but for some reason it has not been updated.
> Alexey
Regards,
MikaL - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
|  |