[Pw_forum] Wall time vs. CPU time

[Vo, Trinh (388C)]

Thank you very much, Paolo.

Trinh


On 8/28/10 11:54 AM, "Paolo Giannozzi" <giannozz at democritos.it> wrote:

> 
> On Aug 28, 2010, at 20:14 , Vo, Trinh (388C) wrote:
> 
>> For all my jobs, the wall time is usually significantly larger than
>> the CPU time
>> [...] I don¹t know what are the possible reasons that causes this
>> delay.
> 
> 1) time spent in I/O
> 2) time spent in communications (in parallel execution)
> 
>>  What factors I should look at to fix this problem.
> 
> 1) reduce I/O, or use fast I/O channels
> 2) faster communication hardware, or usage of parallelization
> levels requiring less communications.
> 
> More in the user guide
> 
> P.
> ---
> Paolo Giannozzi, Dept of Physics, University of Udine
> via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
> 
> 
> 
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