[Click] Problems with RatedUnqueue

[Eddie Kohler]

Øivind,

Did you ever try the newer Git sources to verify whether this problem still 
occurs there?

Eddie


Øivind Kure wrote:
> Hi,
> I run click in userspace (on a Suse 10.0 machine), essentially as a link emulator.
> The essence of the configuration is Fromdevice ->Queue -> shaper -> Todevice.
> In addition I use  a standard setup with Classifier, IPClassifier, CheckIPHeader, ArpResponder and ArpQuerier, so the configuration acts as a forwarding element.
> 
> For the shaper element I started out with RatedUnqueue . 
> The configuration is used in a controlled environment where the load is  1,5 Mbit/sec MPEG2 video or roughly 150 packets a second.  The configuration works with no problem. However, when I reduce the rate of the shaper element (f. ex 30) , the configuration become CPU bound. Packets are dropped from the video, but the queuing element before the shaper reports 0 drops. The cpu load reported by top increases to 0% idle and almost 100% to click. The machine remains cpu bound until the rate in the shaper element is increased to 250, well above the offered load.
> This problem has been observed for click 1.5 and click 1.6.  I have also observed similar problems on other linux versions.
> 
> If I replace the shaper element with Burster ( which is timer based) , the problem disappears. When the rate in the shaper element  is reduced, the queue starts dropping packets, as is shoul. The cpu load remains almost constant and low.
> 
> It might be designed feature I have missed, a bug, or I might have misunderstood something basic. Any explanation to the observed behaviour will be appreciated. 
> Regards
> Øivind Kure
> 
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