Re: [dpdk-dev] [PATCH] [RFC] vhost: inroduce operation to get vDPA queue stats

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 4/10/20 4:15 PM, Matan Azrad wrote:
> 
> 
> From: Maxime Coquelin
>> Sent: Friday, April 10, 2020 5:04 PM
>> To: Matan Azrad <matan@mellanox.com>; dev@dpdk.org
>> Cc: Slava Ovsiienko <viacheslavo@mellanox.com>; Shahaf Shuler
>> <shahafs@mellanox.com>; Xiao Wang <xiao.w.wang@intel.com>; Tiwei Bie
>> <tiwei.bie@intel.com>
>> Subject: Re: [PATCH] [RFC] vhost: inroduce operation to get vDPA queue
>> stats
>>
>>
>>
>> On 4/10/20 3:54 PM, Matan Azrad wrote:
>>> Hi Maxime
>>>
>>> From: Maxime Coquelin
>>>> Hi Matan,
>>>>
>>>> On 3/16/20 4:12 PM, Matan Azrad wrote:
>>>>> The vDPA device offloads all the datapath of the vhost device to the
>>>>> HW device.
>>>>>
>>>>> In order to expose to the user traffic information this patch
>>>>> introduce new API to get traffic statistics per virtio queue.
>>>>>
>>>>> The statistics are taken directly from the vDPA driver managing the
>>>>> HW device.
>>>>
>>>> Shouldn't the stats be collected from the PF like for "legacy" SR-IOV
>>>> via the sysfs?
>>>> Something like:
>>>> /sys/class/net/<PF name>/device/sriov/<VF ID>/stats/
>>>
>>> Yes, probably, statistics can be taken from sysfs.
>>>
>>> But we are introducing a DPDK API to get the virtio statistics.
>>> So, driver which can take statistics from there can take them from sysfs in
>> the driver operation.
>>>
>>> In addition, the API includes per virtio queue statistics and in virtio data-
>> path terms, it is very helpful for debuggability.
>>
>> Ok, the per queue stats is a valid point for queue debug.
>>
>> Even if we add this API, I still think we should ensure the stats will be
>> available through the sysfs, so that it makes Kubernetes integration seemless
>> wrt to legacy SR-IOV[0].

Just noticed I missed to paste the link:

[0]:
https://github.com/killianmuldoon/node_exporter/commit/3e0b931e6526e68aa7192e6bca31ceb892d62754

> 
> For Mellanox legacy SRIOV the sysfs stats you mentioned are available.

Cool! I'll review your series next week.

Thanks,
Maxime

>> Also, it would provide a single way to get statistics for both DPDK and Kernel
>> vDPA.
> 
> Sure.
> 
>> Thanks,
>> Maxime
>>
>>>
>>>
>>>> Regards,
>>>> Maxime
>>>
>