[e2e] TCP Delayed Ack

[Joe Touch]

Baruch Even wrote:
> Saikat Guha wrote:
>> On Fri, 2006-02-17 at 12:10 +0000, Baruch Even wrote:
>>
>>> Antonio Pinizzotto wrote:
>>>
>>>> Do you know about a way to disable the TCP Delayed Ack on Linux?
>>> There is no switch in Linux to do that.
>>
>> Have you tried the TCP_NODELAY socket option that disables Nagle?

That addresses how data is (or is not) aggregated at the sender to avoid
more than one outstanding (unack'd) partial segment. It doesn't deal
with the ACKs.

>> There
>> is also a TCP_QUICKACK socket option.
>>
>> Check the manpage for tcp(7) for details.
> 
> I didn't notice this option but it still wouldn't solve the issue of
> completely disabling delayed-acks.
> 
> It might be useful to an application that for some reason wants to force
> acks, it's not so useful for experiments where you want to completely
> avoid delayed-acks. The manpage says the effect is temporary and so it
> also seems from the code.

Why is the application forcing ACKs? What's the utility, other than to
trick the other side to open its window faster than recommended?

Joe