Re: [dpdk-dev] [PATCH 21.05] app/testpmd: support show Rx queue count

[Lance Richardson <lance.richardson@broadcom.com>]

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On Fri, Feb 12, 2021 at 6:51 AM Ferruh Yigit <ferruh.yigit@intel.com> wrote:
>
> On 2/11/2021 7:44 PM, Lance Richardson wrote:
> > Add support for querying receive queue count in order to allow
> > the rte_eth_dev rx_queue_count() API to be exercised and tested.
> >
>
> +1 to adding this feature, but the naming is a little misleading, "Rx queue
> count", it looks like it will print the number of Rx queues, and the API has the
> same problem indeed.
>
> Can you please clarify it that it is to get number of used descriptor in a Rx queue?
> And "used descriptor" part also needs some explanation I think.
>
That makes sense, fixed in v2.

>
> There is already an existing command:
> "show port <port_id> rxq|txq <queue_id> desc <desc_id> status"
>
> What do you think adding the new one as something like:
> "show port <port_id> rxq <queue_id> desc used count"

Sounds good, v2 is updated to use that form.

> > +show rxq count
> > +~~~~~~~~~~~~~~~~~~~~~~~~~
>
> The '~' line length should be same as header length
>

Fixed in v2.

> > +
> > +Display the number of ready descriptors on a given RX queue::
>
> Can you please describe more, what is "ready descriptor"?
>
> The 'rte_eth_rx_queue_count()' API should be returning number of descriptors
> filled by HW.
>

I took a stab at this in v2, but maybe it could be expanded more.

As I understand it, the returned descriptor count should correspond to
the number of packets that could be received in the next call to the burst
receive function... not necessarily the hardware-specific notion of a
descriptor, which might include descriptors used for chained mbufs,
LRO metadata, async status messages from firmware, etc.

Thanks,

    Lance