Issues with a Large Fat pipe Network simulation

[Pieter de Boer]

Luigi Rizzo wrote:

>>However.. when I deleted the pipe rules on 'network', the speed suddenly 
>>went up to around 800mbit/s too! I remade them, and voila, 200mbit/s.
> network emulation is a tricky job :)
It sure is, so I'm happy you're trying to help out :)

> in any case i believe what happens is the following.
> 
> The pipe has a default size of 50 slots, which at 1500 bytes is
> little above 64k. If the sender is bursting a large number of packets,
> it may well overflow the pipe's queue causing a backoff (which
> may simply be immediate, or delayed, depending on how you configure
> various things).
> 
> I believe setting the queue size in the pipe to a value larger than
> the window should fix things.
I had the same thought, so I already fiddled with it a bit. Because you
brought it up I tested the following this evening:
send/recv spaces at 128KB

00001: unlimited    0 ms   50 sl. 1 queues (1 buckets) droptail
00002: unlimited    0 ms   50 sl. 1 queues (1 buckets) droptail

I'm getting 300-400mbit/s (which is higher than yesterday; it seems the
speed creeps up a bit after a while).


00001: unlimited    0 ms  100 sl. 1 queues (1 buckets) droptail
00002: unlimited    0 ms  100 sl. 1 queues (1 buckets) droptail

I'm getting 300-400mbit/s.

There doesn't seem to be a direct relation between the pipe's queuing
slots and the throughput. Setting the send/recvspaces to 65535 again
does give me an immediate throughput of >800mbit/s, though.


Hope you still have some other ideas, since I'm a bit puzzled here..

-- 
Pieter