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<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">I am doing the following thing.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Step 1. Create DM object and get global vector ‘V’ using DMGetGlobalVector.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Step 2. Doing some parallel operations on V.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Step 3. I am using VecScatterCreateToAll on V to create a sequential vector ‘V_SEQ’ using VecScatterBegin/End with SCATTER_FORWARD.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Step 4. I am performing an expensive operation on V_SEQ and outputting the updated V_SEQ.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Step 5. I am using VecScatterBegin/End with SCATTER_REVERSE (global and sequential flipped) to get V that is updated with new values from V_SEQ.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Step 6. I continue using this new V on the rest of the parallelized program.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Question: Suppose I have n MPI processes, is the expensive operation in Step 4 repeated n times? If yes, is there a workaround such that the operation in Step 4 is performed only once? I would
like to follow the same structure as steps 1 to 6 with step 4 only performed once.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Vysakh Venugopal<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0in">---<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0in">Vysakh Venugopal</span><span style="font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0in">Ph.D. Candidate</span><span style="font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0in">Department of Mechanical Engineering</span><span style="font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-family:"Arial",sans-serif;color:black;border:none windowtext 1.0pt;padding:0in">University of Cincinnati, Cincinnati, OH 45221-0072</span><span style="font-family:"Arial",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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