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Subject: Re: [OMPI users] calling a customized MPI_Allreduce with MPI_PACKED datatype
From: Massimo Cafaro (massimo.cafaro_at_[hidden])
Date: 2011-02-06 18:28:49


hi Jody,

yes, the buffer sizes are actually quite huge with regard to the actual data to be packed.unpacked.

Massimo

On Feb 6, 2011, at 10:44 PM, jody wrote:

> Hi Massimo
>
> Just to make sure: usually the MPI_ERR_TUNCATE error is caused by
> buffer sizes that are too small.
> Can you verify that the buffers you are using are large enough to
> hold the data they should receive?
>
> Jody
>
>
> On Sat, Feb 5, 2011 at 6:37 PM, Massimo Cafaro
> <massimo.cafaro_at_[hidden]> wrote:
>> Dear all,
>>
>> in one of my C codes developed using Open MPI v1.4.3 I need to call MPI_Allreduce() passing as sendbuf and recvbuf arguments two MPI_PACKED arrays. The reduction requires my own MPI_User_function that needs to MPI_Unpack() its first and second argument, process them and finally MPI_Pack() the result in the second argument.
>>
>> I need to use MPI_Pack/MPI_Unpack because I am not able to create a derived datatype, since many data I need to send are dynamically allocated.
>> However, the code fails at runtime with the following message:
>>
>> An error occurred in MPI_Unpack
>> on communicator MPI_COMM_WORLD
>> MPI_ERR_TRUNCATE: message truncated
>> MPI_ERRORS_ARE_FATAL (your MPI job will now abort)
>>
>> I have verified that, after unpacking the data in my own reduction function, all of the data are wrong.
>> Is this possible in MPI? I did not find anything on the "MPI reference Volume 1" and "Using MPI" that prevents this. This should just require using as datatype MPI_PACKED in MPI_Allreduce() . However, searching on the web I did not find any examples.
>>
>> Thank you in advance for any clue/suggestions/source code examples.
>> This is driving me crazy now ;-(
>>
>> Massimo Cafaro
>>
>>
>> -
>>
>> *******************************************************************************************************
>>
>> Massimo Cafaro, Ph.D. Additional affiliations:
>> Assistant Professor Euro-Mediterranean Centre for Climate Change
>> Dept. of Engineering for Innovation SPACI Consortium
>> University of Salento, Lecce, Italy E-mail massimo.cafaro_at_[hidden]
>> Via per Monteroni massimo.cafaro_at_[hidden]
>> 73100 Lecce, Italy cafaro_at_[hidden]
>> Voice/Fax +39 0832 297371 cafaro_at_[hidden]
>> Web http://sara.unisalento.it/~cafaro
>>
>>
>> *******************************************************************************************************
>>
>>
>>
>>
>>
>>
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>
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-

*******************************************************************************************************

 Massimo Cafaro, Ph.D. Additional affiliations:
 Assistant Professor Euro-Mediterranean Centre for Climate Change
 Dept. of Engineering for Innovation SPACI Consortium
 University of Salento, Lecce, Italy E-mail massimo.cafaro_at_[hidden]
 Via per Monteroni massimo.cafaro_at_[hidden]
 73100 Lecce, Italy cafaro_at_[hidden]
 Voice/Fax +39 0832 297371 cafaro_at_[hidden]
 Web http://sara.unisalento.it/~cafaro
       

*******************************************************************************************************



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