Dear Prof. Sherwin,<div>Thanks for your reply. The motivation behind this problem is that the projection process is called during each iteration step within a field smoothing function.Therefore, the computational cost is crucial for the overall efficiency. I am still figuring out alternative ways to do this. Hopefully, I could attend the workshop and get more help.</div><div>Best</div><div>Jian&nbsp;<br><br><br><blockquote name="replyContent" style="padding-left:5px;margin-left:5px;border-left:#b6b6b6 2px solid;margin-right:0">-----原始邮件-----<br>
<b>发件人:</b> "Sherwin, Spencer J" &lt;s.sherwin@imperial.ac.uk&gt;<br>
<b>发送时间:</b> 2016年5月26日 星期四<br>
<b>收件人:</b> "Jian Yu" &lt;yuj@buaa.edu.cn&gt;<br>
<b>抄送:</b> nektar-users &lt;nektar-users@imperial.ac.uk&gt;<br>
<b>主题:</b> Re: [Nektar-users] Parallel Problem with FieldConvert<br><br>




Hi Jian,
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<div class="">Sorry for the slow response, this is grading time in the UK.&nbsp;</div>
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<div class="">This might be due to the preconditioners not being very smart in 2D. I think there might be a BlockDiagonal preconditioned in 2D which could possibly work much better. In 3D we have a number of preconditioners set up.&nbsp;</div>
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<div class="">I probably need to have a look at this but may not get a chance until you are over in a couple of weeks.</div>
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<div class="">Cheers,</div>
<div class="">Spencer.</div>
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<div class="">On 25 May 2016, at 02:04, Jian Yu &lt;<a href="mailto:yuj@buaa.edu.cn" class="" target="_blank">yuj@buaa.edu.cn</a>&gt; wrote:</div>
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<div class="">Dear all,
<div class="">I encountered a problem when I run the FieldConvert with two or more cpu cores for the C0Projection module.</div>
<div class="">For example, when I run the following command, it is OK:</div>
<div class="">mpirun -np 1 ./FieldConvert -m C0Projection 2D_20x20.xml 2D_20x20_0.chk 2D_20x20_0_C0.fld</div>
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<div class="">However, the following command will report an error:</div>
<div class="">mpirun -np 2 ./FieldConvert -m C0Projection 2D_20x20.xml 2D_20x20_0.chk 2D_20x20_0_C0.fld&nbsp;</div>
<div class="">and the error message is:</div>
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<div class="">gs_setup: 60 unique labels shared</div>
<div class="">&nbsp; &nbsp;pairwise times (avg, min, max): 0.000110245 0.00010879 0.000111699</div>
<div class="">&nbsp; &nbsp;crystal router &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: 9.22918e-05 9.22918e-05 9.22918e-05</div>
<div class="">&nbsp; &nbsp;all reduce &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;: 0.000179148 0.0001791 0.000179195</div>
<div class="">&nbsp; &nbsp;used all_to_all method: crystal router</div>
<div class="">&nbsp; &nbsp;handle bytes (avg, min, max): 4724 4724 4724</div>
<div class="">&nbsp; &nbsp;buffer bytes (avg, min, max): 1920 1920 1920</div>
<div class="">CG iterations made = 5001 using tolerance of 1e-09 (error = nan, rhs_mag = inf)</div>
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<div class="">Fatal &nbsp; : Level 0 assertion violation</div>
<div class="">Exceeded maximum number of iterations</div>
<div class="">terminate called after throwing an instance of 'ErrorUtil::NekError'</div>
<div class="">&nbsp; what(): &nbsp;Level 0 assertion violation</div>
<div class="">Exceeded maximum number of iterations</div>
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<div class="">Can anyone help me about this?</div>
<div class="">Best&nbsp;</div>
<div class="">Jian</div>
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<div class="">Spencer &nbsp;Sherwin</div>
<div class="">McLaren Racing/Royal Academy of Engineering Research Chair,&nbsp;</div>
<div class="">Professor of Computational Fluid Mechanics,</div>
<div class="">Department of Aeronautics,</div>
<div class="">Imperial College London</div>
<div class="">South Kensington Campus</div>
<div class="">London SW7 2AZ</div>
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<div class=""><a href="mailto:s.sherwin@imperial.ac.uk" class="" target="_blank">s.sherwin@imperial.ac.uk</a></div>
<div class="">+44 (0) 20 759 45052</div>
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