On Thu, 2017-11-30 at 09:51 -0500, Neal Cardwell wrote:
> On Thu, Nov 30, 2017 at 5:24 AM, Eric Dumazet <eric.dumazet@gmail.com
> > wrote:
> > I agree that TCP itself should generate ACK smarter, on receivers
> > that
> > are lacking GRO. (TCP sends at most one ACK per GRO packets, that
> > is
> > why we did not feel an urgent need for better ACK generation)
> >
> > It is actually difficult task, because it might need an additional
> > timer, and we were reluctant adding extra complexity for that.
>
> How about just using the existing delayed ACK timer, and just making
> the delayed ACK logic a bit smarter? We could try using the existing
> logic and timers, but using something adaptive instead of the magic
> "2" MSS received to force an ACK.
Keep in mind some distros have HZ=250 or even HZ=100
So even a 'one jiffie' timer could add 10ms delay.