[nvmewin] Implementing Arbitration in the community driver

[Sagi Bar]

Hello,

I am currently reviewing the community driver and have the following question:

I would like to experiment with Weighted Round Robin arbitration.

I see that I can set the arbitration using the community driver implementation of the NVME "Set Features" command.

However, in order to use a weighted RR, queue priority should be set.

AFAIK, the only time you can set the Submission Queue priority is during the Queue creation, which is done automatically by the driver.

The field is defined in the "ADMIN_CREATE_IO_SUBMISSION_QUEUE_DW11" structure.

    /*
     * [Queue Priority] This field indicates the priority service class to use
     * for commands within this Submission Queue. This field is only used when
     * the weighted round robin with an urgent priority service class is the
     * arbitration mechanism is selected. Refer to section 4.7. Value 00b ==
     * Urgent, Value 01b == High, Value 10b == Medium, Value 11b == Low.
     */
    ULONG   QPRIO   :2;


My question is :

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.
This is due to the fact that I don't see a way of settings Submission Queue priority after the queue is created.

Do you think that there is an easier way to do that ?

Sagi Bar
Test & Tools Staff FW Engineer
[cid:image001.png at 01CEA3CD.FE1957E0]
7 Atir Yeda St, Kfar - Saba 44425, Israel

sagi.bar at SanDisk.com<mailto:sagi.bar at SanDisk.com>


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