Re: [Make-wifi-fast] debugging TCP stalls on high-speed wifi

In my application this is a bridge or router (not TCP endpoint), and the driver is doing GRO and NAPI polling. Also looking at using the skb->fraglist to make the GRO code more effective and more transparent by passing flags, short segments, etc through for perfect reconstruction by TSO.

Simon

On Dec 12, 2019, at 5:46 PM, Eric Dumazet [off-list ref] wrote:



On 12/12/19 4:59 PM, Simon Barber wrote:

quoted

I’m currently adding ACK thinning to Linux’s GRO code. Quite a simple addition given the way that code works.

Simon

Please don't.

1) It will not help since many NIC  do not use GRO.

2) This does not help if you receive one ACK per NIC interrupt, which is quite common.

3) This breaks GRO transparency.

4) TCP can implement this in a more effective/controlled way,
  since the peer know a lot more flow characteristics.

Middle-box should not try to make TCP better, they usually break things.