Re: Possible bug from kernel 2.6.22 and above, 2.6.24-rc4

[Ingo Molnar]

* Jie Chen <chen@xxxxxxxx> wrote:

> Since I am using affinity flag to bind each thread to a different 
> core, the synchronization overhead should increases as the number of 
> cores/threads increases. But what we observed in the new kernel is the 
> opposite. The barrier overhead of two threads is 8.93 micro seconds vs 
> 1.86 microseconds for 8 threads (the old kernel is 0.49 vs 1.86). This 
> will confuse most of people who study the 
> synchronization/communication scalability. I know my test code is not 
> real-world computation which usually use up all cores. I hope I have 
> explained myself clearly. Thank you very much.

btw., could you try to not use the affinity mask and let the scheduler 
manage the spreading of tasks? It generally has a better knowledge about 
how tasks interrelate.

	Ingo
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