Re: Too aggressive TCP ACKs

On Wed, Oct 26, 2022 at 02:55:21PM +0200, tuexen@freebsd.org wrote:
> > On 26. Oct 2022, at 10:57, Tom Jones <thj@freebsd.org> wrote:
> > 
> > On Sat, Oct 22, 2022 at 12:14:25PM +0200, Hans Petter Selasky wrote:
> >> Hi,
> >> 
> >> Some thoughts about this topic.
> >> 
> >> Delaying ACKs means loss of performance when using Gigabit TCP 
> >> connections in data centers. There it is important to ACK the data as 
> >> quick as possible, to avoid running out of TCP window space. Thinking 
> >> about TCP connections at 30 GBit/s and above!
> >> 
> >> I think the implementation should be exactly like it is.
> >> 
> >> There is a software LRO in FreeBSD to coalesce the ACKs before they hit 
> >> the network stack, so there are no real problems there.
> >> 
> > 
> > Changing the ACK ratio seems to be okay in most cases, a paper I wrote
> > about this was published this week:
> > 
> > https://onlinelibrary.wiley.com/doi/10.1002/sat.1466
> > 
> > It focuses on QUIC, but congestion control dynamics don't change with
> > the protocol. You should be able to read there, but if not I'm happy to
> > send anyone a pdf.
> Is QUIC using an L=2 for ABC?

I think that is the rfc recommendation, actual deployed reality is more
scattershot.

- Tom