Re: debugging TCP stalls on high-speed wifi

On 1/24/20 2:34 AM, Johannes Berg wrote:

On Fri, 2019-12-13 at 14:40 +0530, Krishna Chaitanya wrote:

quoted

Maybe try 'reno' instead of 'cubic' to see if congestion control is
being too careful?

I played around with this a bit now, but apart from a few outliers, the
congestion control algorithm doesn't have much effect. The outliers are

 * vegas with ~120 Mbps
 * nv with ~300 Mbps
 * cdg with ~600 Mbps

All the others from my list (reno cubic bbr bic cdg dctcp highspeed htcp
hybla illinois lp nv scalable vegas veno westwood yeah) are within 50
Mbps or so from each other (around 1.45Gbps).

When the stalls happens, what is causing TCP to resume the xmit ?

Some tcpdump traces could help.

(-s 100 to only capture headers)