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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Hi Cheng,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Perhaps you could try asking in the following mailing lists for verbs related questions:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:10.0pt;font-family:"Segoe UI",sans-serif">linux-rdma@vger.kernel.org
<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-size:11.0pt">users@lists.openfabrics.org.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",sans-serif;color:#1F497D">Arun.<o:p></o:p></span></p>
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<p class="MsoNormal"><a name="_____replyseparator"></a><b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Libfabric-users [mailto:libfabric-users-bounces@lists.openfabrics.org]
<b>On Behalf Of </b>Dave Goodell (dgoodell)<br>
<b>Sent:</b> Saturday, September 03, 2016 7:18 AM<br>
<b>To:</b> Cheng Wang <wangchenghku@gmail.com><br>
<b>Cc:</b> libfabric-users@lists.openfabrics.org<br>
<b>Subject:</b> Re: [libfabric-users] ibv_post_send() execution time<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Cheng,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Your question is about libibverbs but this list is for libfabric. Perhaps someone else on this list knows the appropriate venue for your question. <br>
<br>
-Dave<o:p></o:p></p>
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On Sep 2, 2016, at 11:57 PM, Cheng Wang <<a href="mailto:wangchenghku@gmail.com">wangchenghku@gmail.com</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">Hi,</span> <o:p></o:p></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">I am new to OFI and I am doing some microbenchmarks.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">I measured the execution time of ibv_post_send() in both rping(ping-pong) program and ib_write_lat program. Below is my pseudo code:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">clock_gettime(); // start<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">ibv_post_send();<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">clock_gettime(); // end<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">Specifically, I measured IBV_WR_RDMA_WRITE operation using the same data size in Reliable Connection (RC) mode.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">And the result shows each ibv_post_send() in rping takes around 170~180 nanoseconds to return, but in ib_write_lat program it only takes around 60 nanoseconds to return in average.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">I suspected that this is caused by memalign of the sent buffer in ib_write_lat. But after I changed the rdma sent buffer in rping to be also memory aligned, it still takes around 170 nanoseconds.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">May I know what caused this difference?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.5pt">Many thank in advance.<o:p></o:p></span></p>
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<p class="MsoNormal">_______________________________________________<br>
Libfabric-users mailing list<br>
<a href="mailto:Libfabric-users@lists.openfabrics.org">Libfabric-users@lists.openfabrics.org</a><br>
<a href="http://lists.openfabrics.org/mailman/listinfo/libfabric-users">http://lists.openfabrics.org/mailman/listinfo/libfabric-users</a><o:p></o:p></p>
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