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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi Paul,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I would *<b>highly</b>* recommend you initially test vlbi_fake is producing the VDIF data you expect. Try running it independently with some sort of VDIF (or generic) UDP receiver to test. I have
some of my own code you can use if you don’t have anything yourself.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">A few other suggestions/comments:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<ul style="margin-top:0cm" type="disc">
<li class="MsoListParagraph" style="margin-left:18.0pt;mso-list:l0 level1 lfo1"><span style="mso-fareast-language:EN-US">Avoid 5000 byte VDIF frames. That is some hang up from Mark5B 10K frames I think and has no purpose. Something closer to 8k (e.g. 8000 pr
8192 + header) makes more sense. Try “9000”.<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:18.0pt;mso-list:l0 level1 lfo1"><span style="mso-fareast-language:EN-US">Vlbi_fake chooses a frame size which makes sense based on the data rate AND networking parameters, the 5000 probably include VDIF header
and maybe network headers (I forget). You do need to setup. DIFX to match the frame size vlbi_fake uses, so some experimentation may ne needed<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:18.0pt;mso-list:l0 level1 lfo1"><span style="mso-fareast-language:EN-US">Are you sure “Jumbo frames” are enabled (ie 9000 byte MTU enabled everywhere)<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:18.0pt;mso-list:l0 level1 lfo1"><span style="mso-fareast-language:EN-US">Make sure the “threads” usage matches what you expect<o:p></o:p></span></li></ul>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Cheers<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Chris<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Difx-users <difx-users-bounces@listmgr.nrao.edu> on behalf of Paul Harrison via Difx-users <difx-users@listmgr.nrao.edu><br>
<b>Date: </b>Tuesday, 30 November 2021 at 10:50<br>
<b>To: </b>difx-users@listmgr.nrao.edu <difx-users@listmgr.nrao.edu><br>
<b>Subject: </b>[Difx-users] VDIF Benchmarking {External}<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi,<br>
<br>
I am trying to do some benchmarking of DiFX 2.6.2 with the aim of sizing a cluster for e-MERLIN - I am attempting to run some VDIF tests on a cluster that I have access to with some 1Gb/s interfaces - so I am using as my starting point a 1Gb/s EVN NME - eMERLIN
usually supplies VDIF a single 64MHz IF band 2 bit sampled with 2 threads. I am trying to send live VDIF with vlbi_fake<br>
<br>
<br>
vlbi_fake -H ${ip[$i]} -year 2020 -dayno 305 -time 11:07:00 -novtp -p 12345 -bandwidth 64 -framesize 5000 -udp 5000 -vdif -d 300 -b 2 -nthread 2<br>
<br>
but mpifxcorr just sits there - well it says things like<br>
<br>
2021-11-29 18:11:46,181 DiFXAlert INFO MPI[-1] compute-0-12.local libmark6sg libmark6sg started<br>
<br>
when it detects that the stream has started - I think that I have got the frame sizes correct as when they were not correct mpifxcorr was saying so (I had started with the “default” 5000 and then noticed that vlbi_fake was announcing that it was doing a framesize
of 4096)<br>
<br>
I enclose the contol files, and I would be grateful if anyone has any tips for getting this to run<br>
<br>
Cheers<br>
Paul.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
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