Re: [Openvpn-users] tcp-client: large ping during transfers (fwd)

[Antonio Q. <a...@un...>]

On 10/11/17 03:00, Gert Doering wrote:
> Hi,
> 
> On Thu, Nov 09, 2017 at 01:21:56PM -0500, Selva wrote:
>> So I do feel that high latency under load is not a fundamental limitation
>> -- probably
>> openvpn with --proto tcp is not trying hard to manage the queue smartly?
> 
> It isn't.  It's just stuffing packets into the tcp stream as they come
> out the tun/tap fd.
> 
> What we *could* do is make the socket buffer much smaller and have a
> larger internal queue in openvpn, and then do smart stuff, like "move
> small packets in front of full-sized TCP packets", "random early drop"
> and all that stuff people have done research on over the last 20 years.  
> 
> But that's quite a bit of work...

On top of that, adding another queue is likely going to increase the
bufferbloat effect. We already have the kernel doing its own stuff and
we should try to add more "smart" things on top.

(not relevant for this thread itself, but I thought it was worth
pointing out)

Cheers,

-- 
Antonio Quartulli