[Bloat] [Cerowrt-devel] uplink bufferbloat and scheduling problems

[David Lang]

On Thu, 2 Dec 2021, Dave Collier-Brown wrote:

> A different hand-wave: what about "packet trains"? They make using
> queuing networks mis-estimate, do they come close together enough that
> routers need to be sensitive to them, and affect the number of packets
> they need to buffer?

I think that's going to depend on how big the burst is, and how sensitive it is 
to packet loss. If it's not big, and is sensitive to packet loss, then it's not 
a big deal to buffer it. But if it's 'too big', it will interfere with others.

since it's impossible to know how big they are going to be, especially compared 
to others, it seems to work pretty well to just not try to account for them.

I believe that current best options do give new flows a bit more leeway before 
throttling them, so if it is a small burst at the start of a flow, it will go 
through quickly, and only start getting throttled if the volume remains high.

Remember, perfect is the enemy of better. You can always craft a case where 
perfect knowledge of future traffic would let you optimize in a different way, 
but since such knowledge doesn't exist in the real world, attempts to account 
for everything are doomed to failure.

David Lang