[Click] multithread vs. single thread

[Roman Chertov]

I should have read the SMP Click paper before I posted this.  Adding 
additional Queue elements has helped somewhat.

Roman Chertov wrote:
> Hello,
> 	Now that I am more knowledgeable about the multithreaded details I want 
> to ask the following question.  I have a configuration where I have two 
> NICs that send packets in both direction at the same rates.  In the 
> device driver I have a tiny bit of code which embeds timestamps into the 
> packets, so I know the traversal time of the packet from one card to 
> another (polling overheads add some noise).  As I raise the rates the 
> average delays increase and tend to vary from run to run.  I have tried 
> to use StaticThreadSched to assign ToDevice/PollDevice elements to 
> separate threads to reduce the noise due to polling. (the longer it 
> takes to schedule a PollDevice the longer the packet delay will be). 
> However, it appears that I get better results when I don't use any 
> threading at all.  I would have thought that using --enable-task-heap 
> and assignment of PollDevice to separate threads would have improved the 
> performance.  Any insight into this would be greatly appreciated.
> 
> Many Thanks,
> 
> Roman
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