[Pw_forum] Use of pool

[Liping Yu]

Dear Huiqun,

If your results are based on the same number of processes for different
npools, they make sense to me.   To my understanding, the almost linear
time scaling of using npool means that the computer time is almost
linear to npool (and also the total number of procs) only when we fix
the number of the processors at each pool.

Please correct me if I am wrong. Thanks!

Liping Yu
Department of Physics
NC State University, USA


Huiqun Zhou wrote:
> Dear list users:
>
> I happened to test duration times of calculating the system I'm 
> investigating against number of pools used. There are totally
> 36 k points. But the results surprised me quite a lot. 
>
> no pool:  6m21.02s CPU time,     6m45.88s wall time
> 2 pools:  7m19.39s CPU time,     7m38.99s wall time
> 4 pools: 11m59.09s CPU time,    12m14.66s wall time
> 8 pools: 21m28.77s CPU time,    21m38.71s wall time
>
> The machine I'm using is an AMD box with 2 quad core shanghai.
>
> Is my understanding of usage of pool wrong?
>
> Huiqun Zhou
> @Nanjing University, China
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