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: Drop `accumulation of large send credits' patch

RFC PATCH New Gerrit Renker 1 participant 1 message Jul 21, 2007

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While bisecting I found that the DCCP packet scheduler now reacts much differently from the one 2.6.20 (which was up to three times too fast).

The new experimental data, taken on a 2.6.22 tree with the DCCP test tree patches, shows that

(1) the packet scheduler now reacts accurately with regard to the value of t_ipi;
(2) the send-credits patch is no longer necessary and in fact degrades performance.

I would therefore like to drop this patch from the test tree.

The results are here:
http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/packet_scheduling/2.6.22-scheduler/

The most drastic example was a laptop with HZ%0
* 2.6.22 netdev as of 20/7: 84.6 Mbits/sec
* DCCP test tree as of 20/7: 4.33 Mbits/sec !!!
* DCCP test tree patched: 92.8 Mbits/sec

I would be grateful for any test results and continue to look for further causes of the bad performance with the TBF bandwidth restriction.

Any input, suggestions, test reports are welcome.