[Click] MSQueue induced latency

[Eddie Kohler]

Hi Beyers,

MSQueue is not one of our more up-to-date elements.  It was optimized for a 
particular benchmark, long ago.  Try undefining the BATCHING symbol, which can 
prevent pulls from succeeding when there are relatively few packets in the 
queue; let us know what happens.

Eddie


Beyers Cronje wrote:
> Hi,
> 
> As with my previous email I'm running a simple switch configuration:
> 
> sw :: EtherSwitch;        //MT enabled etherswitch
> out0 :: MSQueue -> ToDevice(eth0);
> out1 :: MSQueue -> ToDevice(eth1);
> PollDevice(eth0, PROMISC true) -> [0]sw;
> PollDevice(eth1, PROMISC true) -> [1]sw;
> sw[0] -> out0; 
> sw[1] -> out1;
> 
> I've compiled click with multithreading enabled and using
> click-install with the -t option.
> When doing a ping through the switch between two devices located on
> segments directly conencted to eth0 and eth1 I get an average ping
> time of 25ms. This is obviously way too high.
> 
> Using the same setup replacing only MSQueue with CPUQueue (or even
> simple Queue under single thread Click) I get an average ping time of
> <1ms.
> 
> Another test involved copying a 500MB file between the two end
> devices. With MSQueue I got an average of around 6MB per second, while
> with CPUQueue I got over 9MB per second.
> 
> Any idea why MSQueue will introduce so much latency?
> 
> Kind regards
> 
> Beyers
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