[Omp] First Touch Inicialization

[Federico Massaioli]

The size in bytes of the variables listed on the threadprivate clause, as 
well as an estimate of the actual amount of computation performed in the 
test should be specified as well.
What are you listing on the threadprivate? A few scalars or a big array?

Regards
Federico

On Wed, 8 Mar 2006, eric duncan wrote:

> When making comments like this, it would be helpful if you specified the
> type of machine, operating system, and compiler you are using.  I don't
> think that this is accurate as a general statement and may well vary
> considerably from one compiler version (or machine, or OS, etc) to the next.
>
> Patricia Bittencourt Sampaio wrote On 03/08/06 09:47,:
>>  Hello,
>>
>>      As an extension of the previus messages related
>> to initialization. I've found out recently that when
>> threadprivate variables are used on a parallel region
>> it demands a considerable overhead for the
>> initialization of these variables.
>>      And besides that, this overhead exists even when
>> just one thread is used (when OMP_NUM_THREADS=1).
>>      I have executed a program with a parallel region
>> for the initialization, compiling that program with
>> and without OpenMP directives. My intend was to verify
>> if OpenMP directives generate some overhead.
>>      The directives for Parallel Region does not
>> generate overhead, or if it does, it is not
>> significant. However for the parallel region that use
>> the threadprivate variables, I observe that the
>> computation comprised on at took 80 seconds to
>> conclude, using just one thread. And executing this
>> without openmp directives it took 40 seconds. And
>> these values increase on the same proportial (2x) as
>> additional processors, always as a potencial of 2, are
>> used.
>>
>> regards,
>>
>>
>> Patricia Bittencourt Sampaio
>> ====================================
>> Federal University of Rio de Janeiro
>>
>>
>>
>>
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>
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Federico Massaioli                          CASPUR
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