Hello,
On 8/26/24 10:53 AM, Dragos Tatulea wrote:
>
> On 26.08.24 16:26, Carlos Bilbao wrote:
>> Hello Dragos,
>>
>> On 8/26/24 4:06 AM, Dragos Tatulea wrote:
>>> On 23.08.24 18:54, Carlos Bilbao wrote:
>>>> Hello,
>>>>
>>>> I'm debugging my vDPA setup, and when using ioctl to retrieve the
>>>> configuration, I noticed that it's running in half duplex mode:
>>>>
>>>> Configuration data (24 bytes):
>>>> MAC address: (Mac address)
>>>> Status: 0x0001
>>>> Max virtqueue pairs: 8
>>>> MTU: 1500
>>>> Speed: 0 Mb
>>>> Duplex: Half Duplex
>>>> RSS max key size: 0
>>>> RSS max indirection table length: 0
>>>> Supported hash types: 0x00000000
>>>>
>>>> I believe this might be contributing to the underperformance of vDPA.
>>> mlx5_vdpa vDPA devicess currently do not support the VIRTIO_NET_F_SPEED_DUPLEX
>>> feature which reports speed and duplex. You can check the state on the
>>> PF.
>>
>> According to ethtool, all my devices are running at full duplex. I assume I
>> can disregard this configuration output from the module then.
>>
> Yep.
>
>>>> While looking into how to change this option for Mellanox, I read the following
>>>> kernel code in mlx5_vnet.c:
>>>>
>>>> static void mlx5_vdpa_set_config(struct vdpa_device *vdev, unsigned int offset, const void *buf,
>>>> unsigned int len)
>>>> {
>>>> /* not supported */
>>>> }
>>>>
>>>> I was wondering why this is the case.
>>> TBH, I don't know why it was not added. But in general, the control VQ is the
>>> better way as it's dynamic.
>>>
>>>> Is there another way for me to change
>>>> these configuration settings?
>>>>
>>> The configuration is done using control VQ for most things (MTU, MAC, VQs,
>>> etc). Make sure that you have the CTRL_VQ feature set (should be on by
>>> default). It should appear in `vdpa mgmtdev show` and `vdpa dev config
>>> show`.
>>
>> I see that CTRL_VQ is indeed enabled. Is there any documentation on how to
>> use the control VQ to get/set vDPA configuration values?
>>
>>
> You are most likely using it already through through qemu. You can check
> if the CTR_VQ feature also shows up in the output of `vdpa dev config show`.
>
> What values are you trying to configure btw?
Yes, CTRL_VQ also shows up in vdpa dev config show. There isn't a specific
value I want to configure ATM, but my vDPA isn't performing as expected, so
I'm investigating potential issues. Below is the code I used to retrieve
the configuration from the driver; I'd be happy to send it as a patch if
you or someone else reviews it.
>
> Thanks,
> Dragos
Thanks,
Carlos
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