Re: [UDT] UDT with congestion control

[Yunhong Gu <yu...@la...>]

Hi, Harald,

Once you uncomment the -DCUSTOM_CC option, the default UDT congestion 
control algorithm will not be used any more.

Default window size in UDT is 16 packets and it will not change unless you 
assign a new congestion control algorithm.

Once you specify CTCP, you are using TCP's AIMD algorithm, which usually 
does not work well for long distance links (you mentioned that RTT is 
100ms).

Thanks
Yunhong


On Thu, 2 Mar 2006, Harald schwier wrote:

> Hello,
> i'm doing some performance tests with UDT. Without changing
> any options, appclient shows 950 MB/s (1GB Ethernet, RTT about 100ms).
>
> After i uncomment the -DCUSTOM_CC compile option in ./src/Makefile
> and recompile the library the Performance goes down to 1.7 MB/s without
> changing any Options in appclient.
>
> When i change the socket options with:
> UDT::setsockopt(client,0,UDT_CC,newCCCFactory<CTCP>,sizeof(CCCFactory<CTCP>));
> the performance goes down to 0.2 MB/s.
>
> UDT 2.3
> Compiled with: make -e os=LINUX arch=AMD64
>
> What may be the reason for the poor performance???
>
> Thanks in advance,
> Harald
>
>
>
>
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