[mpich-discuss] How to implement this case

[Xiao Li]

Hi Eric,

Assume I have N workers and M trunks of sending data for each worker
respectively, then I have to create N*M data buffer for MPI_Irecv usage. Is
this method too costly?

Or If I write raw socket programming, is that better? Just like traditional
client/server socket programming? Master listens on port and spawn a new
thread to accept worker's data storage request?

cheers
Xiao

On Mon, Jan 3, 2011 at 2:13 PM, Eric A. Borisch <eborisch at ieee.org> wrote:

> Look at the documentation for MPI_Irecv and MPI_Testany ... these should
> help you do what you want.
>
>  Eric
>
> On Mon, Jan 3, 2011 at 12:45 PM, Xiao Li <shinelee.thewise at gmail.com>wrote:
>
>> Hi MPICH2 people,
>>
>> Now, I have a application that composed of single master and many workers.
>> The application requirement is very simple: workers finish some jobs and
>> send data to master and master store these data into files separately. I can
>> simply use MPI_Send on worker side to send data to master. But master does
>> not know the data sending sequence. Some worker go fast while some are slow.
>> More specifically, suppose there are 5 workers, then the data send sequence
>> may be 1,3,4,5,2 or 2,5,4,1,3. If I just write a for loop for(i=1 to 5) on
>> master side with MPI_Recv to get data, the master and some faster worker
>> have to wait for a long time. I know MPI_Gather can implement this. But I am
>> not sure is MPI_Gather works parallelly or just a sequential MPI_Recv?
>> Another issue is my data is extremely large, more than 1GB data needed to be
>> sent to master. If I divide the data into pieces, I do not think MPI_Gather
>> can work. I also tried to think about raw socket programming, but I do not
>> think it is a good practice. Would you give me some suggestion please?
>>
>> cheers
>> Xiao
>>
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