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<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Hello,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I am currently reviewing the community driver and have the following question:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I would like to experiment with Weighted Round Robin arbitration.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">I see that I can set the arbitration using the community driver implementation of the NVME “</span><b><span style="font-size:10.0pt">Set Features”
</span></b><span style="color:#1F497D">command.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">However, in order to use a weighted RR, queue priority should be set.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">AFAIK, the only time you can set the Submission Queue priority is during the Queue creation, which is done automatically by the driver.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">The field is defined in the “</span><span style="font-family:"Verdana","sans-serif";color:#010001;background:white;mso-highlight:white">ADMIN_CREATE_IO_SUBMISSION_QUEUE_DW11</span><span style="font-family:"Verdana","sans-serif";color:#010001">”
</span><span style="color:#1F497D">structure.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";background:white;mso-highlight:white">
<span style="color:green">/*<o:p></o:p></span></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";color:green;background:white;mso-highlight:white"> * [Queue Priority] This field indicates the priority service class to use<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";color:green;background:white;mso-highlight:white"> * for commands within this Submission Queue. This field is only used when<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";color:green;background:white;mso-highlight:white"> * the weighted round robin with an urgent priority service class is the<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";color:green;background:white;mso-highlight:white"> * arbitration mechanism is selected. Refer to section 4.7. Value 00b ==<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";color:green;background:white;mso-highlight:white"> * Urgent, Value 01b == High, Value 10b == Medium, Value 11b == Low.<o:p></o:p></span></p>
<p class="MsoNormal" style="text-autospace:none"><span style="font-family:"Verdana","sans-serif";color:green;background:white;mso-highlight:white"> */<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana","sans-serif";background:white;mso-highlight:white">
<span style="color:#010001">ULONG</span> <span style="color:#010001">QPRIO</span> :2;</span><span style="font-family:"Verdana","sans-serif""><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Verdana","sans-serif""><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">My question is :<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">It appears that the only way to actually set the WRR priority is to delete all Submission Queues, initially created by the driver and re-create them with the correct weight assigned.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">This is due to the fact that I don’t see a way of settings Submission Queue priority after the queue is created.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D">Do you think that there is an easier way to do that ?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:14.0pt;color:#1F497D">Sagi Bar</span><span style="color:#1F497D"><br>
Test & Tools Staff FW Engineer<br>
</span></b><span style="font-size:12.0pt;font-family:"Times New Roman","serif";color:#1F497D"><img width="61" height="12" id="Picture_x0020_1" src="cid:image001.png@01CFA743.5017ACD0" alt="cid:image001.png@01CEA3CD.FE1957E0"><br>
</span><span style="color:#7F7F7F">7 Atir Yeda St, Kfar – Saba 44425, Israel<br>
<br>
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="color:#1F497D"><a href="mailto:sagi.bar@SanDisk.com"><span style="color:blue">sagi.bar@SanDisk.com</span></a><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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