[Click] generating artificial delay

[Eddie Kohler]

Simon Schuetz wrote:
> Hi,
> I am using the following configuration
> FromDevice(eth0) -> Queue -> DelayUnqueue(0.05) -> ToHost(eth0)
> FromDevice(eth2) -> Queue -> DelayUnqueue(0.05) -> ToHost(eth2)
> This implies a round trip delay of 100ms.
> It works, but I experience severe performance problems.
> I tried to used only
> FromDevice(eth2) -> Queue -> DelayUnqueue(0.1) -> ToHost(eth2)
> so that there is only one queue to handle (but same round trip delay),
> and got the same results. The maximum TCP throughput I measured using
> IPerf is about 2.3 MBit/s. If I unload the click router module, I have a
> round-trip delay of less than 1ms, and a throughput of about 70MBit/s.

Hi Simon,

Why are you sending the packets ToHost?  Why not ToDevice?

Can you measure the performance of

FromDevice(eth0) -> ToHost(eth0)
FromDevice(eth2) -> ToHost(eth2)

-- is it any better?  (I'd guess not.)

Click is not designed to get maximum performance when Linux does most of 
the routing.

Eddie