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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi Rajesh,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks for your response.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I appreciate the clarification regarding
<span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span> and core binding. I have some follow-up questions regarding the behaviour difference between RHEL7 and RHEL8.<o:p></o:p></p>
<ol start="1" type="1">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4">
<b>Why does the same </b><b><span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span></b><b> configuration behave differently on RHEL7 vs. RHEL8?</b><o:p></o:p></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
In RHEL7, CPU binding works as expected, but in RHEL8, the application always binds to core 1. What could be causing this difference?<o:p></o:p></li></ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4">
<b>Process vs. DPDK Core Assignment:</b><o:p></o:p></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
My goal is to assign <b>DPDK to run on core 1</b> while the rest of the process threads are pinned using
<span style="font-size:10.0pt;font-family:"Courier New"">numactl</span>.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
Does <span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span> interfere with CPU affinity settings applied through
<span style="font-size:10.0pt;font-family:"Courier New"">numactl</span>?<o:p></o:p></li></ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4">
<b>Effect of Not Specifying a Core in </b><b><span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span></b><b>:</b><o:p></o:p></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
What happens if we don’t specify a core mask (<span style="font-size:10.0pt;font-family:"Courier New"">-c</span> option) during
<span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span>?<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
Will DPDK inherit the core binding from <span style="font-size:10.0pt;font-family:"Courier New"">
numactl</span>, or does it select cores dynamically?<o:p></o:p></li></ul>
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level1 lfo4">
<b>Does </b><b><span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span></b><b> override
</b><b><span style="font-size:10.0pt;font-family:"Courier New"">numactl</span></b><b> settings?</b><o:p></o:p></li><ul type="circle">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l1 level2 lfo4">
If <span style="font-size:10.0pt;font-family:"Courier New"">numactl</span> is used to pin the application to specific cores, does
<span style="font-size:10.0pt;font-family:"Courier New"">rte_eal_init()</span> override that and reset core affinity?<o:p></o:p></li></ul>
</ol>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Your insights on these questions would be very helpful. Thanks again for your time and support!<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Regards,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Rashi Agarwal.<o:p></o:p></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Rajesh Kumar <rajeshthepro@gmail.com>
<br>
<b>Sent:</b> Wednesday, February 26, 2025 4:27 PM<br>
<b>To:</b> Rashi Agarwal <Rashi.Agarwal@mobileum.com><br>
<b>Cc:</b> users@dpdk.org<br>
<b>Subject:</b> Re: CPU Affinity Not Working in RHEL8 with DPDK 20.05<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p><span style="color:red"> Caution :<strong><span style="font-family:"Calibri",sans-serif">External</span></strong></span><o:p></o:p></p>
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<p class="MsoNormal">Hi Rashi,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Please change the argument to rte_eal_init (), in your code, -c 0x2 will always bind it to 1st core . Change it to "-c", "0x30" for pinning core 4 and 5.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<pre><span style="font-size:10.5pt;color:black">int dpdk_argc = 8; char *dpdk_argv[] = { procName, "-c", "0x2", "--no-huge", filePrefix ,"-m","64" , "--log-level=eal,8"};<o:p></o:p></span></pre>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Thanks,<br>
<b>-Rajesh</b><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Wed, Feb 26, 2025 at 10:25 AM Rashi Agarwal <<a href="mailto:Rashi.Agarwal@mobileum.com">Rashi.Agarwal@mobileum.com</a>> wrote:<o:p></o:p></p>
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<p><strong><span style="font-family:"Calibri",sans-serif;font-weight:normal">Hi DPDK Community,</span></strong><o:p></o:p></p>
<p>I am facing an issue where <strong><span style="font-family:"Calibri",sans-serif">CPU affinity is not working as expected in RHEL8</span></strong> with DPDK 20.05, while it works fine in RHEL7.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>Problem Statement:</b><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <span style="font-family:Symbol">·</span> When running my program with
<span style="font-size:10.0pt;font-family:"Courier New"">numactl -C4,5 ./testRTE</span> on
<b>RHEL7</b>, the worker threads correctly bind to the assigned cores.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">
<span style="font-family:Symbol">·</span> However, on <b>RHEL8</b>, the worker threads always bind to
<b>core 1</b>, ignoring the specified CPU set.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;text-indent:36.0pt">
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>Environment Details:</b><o:p></o:p></p>
<ul type="disc">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l3 level1 lfo1">
<b>DPDK Version:</b> 20.05.0<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l3 level1 lfo1">
<b>OS:</b> RHEL8 (Issue) | RHEL7 (Works Fine)<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l3 level1 lfo1">
<b>CPU Affinity Tool:</b> <span style="font-size:10.0pt;font-family:"Courier New"">
numactl -C</span><o:p></o:p></li></ul>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>Sample Program: </b>Attached<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>Observations:</b><o:p></o:p></p>
<ul type="disc">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l2 level1 lfo2">
In <b>RHEL7</b>, worker threads correctly bind to cores specified using <span style="font-size:10.0pt;font-family:"Courier New"">
numactl -C</span>.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l2 level1 lfo2">
In <b>RHEL8</b>, the threads always bind to <b>core 1</b>, ignoring the CPU set.<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l2 level1 lfo2">
Could DPDK be overriding the CPU affinity in RHEL8?<o:p></o:p></li></ul>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b>Questions:</b><o:p></o:p></p>
<ol start="1" type="1">
<li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo3">
Is there any known change in CPU affinity handling between RHEL7 and RHEL8 affecting DPDK?<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo3">
Does DPDK override thread affinity when <span style="font-size:10.0pt;font-family:"Courier New"">
rte_eal_init()</span> is called?<o:p></o:p></li><li class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto;mso-list:l0 level1 lfo3">
Is there any workaround or EAL flag to ensure that CPU affinity is respected?<o:p></o:p></li></ol>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Any insights or suggestions would be greatly appreciated.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Thanks,<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Rashi Agarwal.<o:p></o:p></p>
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