[PATCH] doc: update TAP device features

[Ferruh Yigit]

On 10/4/2024 3:26 AM, Stephen Hemminger wrote:
> On Fri, 4 Oct 2024 02:48:21 +0100
> Ferruh Yigit <ferruh.yigit at amd.com> wrote:
> 
>> On 9/4/2024 4:42 PM, Stephen Hemminger wrote:
>>> The TAP device does have per-queue stats and handles multi-process.
>>>
>>> Signed-off-by: Stephen Hemminger <stephen at networkplumber.org>
>>> ---
>>>  doc/guides/nics/features/tap.ini | 2 ++
>>>  1 file changed, 2 insertions(+)
>>>
>>> diff --git a/doc/guides/nics/features/tap.ini b/doc/guides/nics/features/tap.ini
>>> index f26355e57f..f2ea5cd833 100644
>>> --- a/doc/guides/nics/features/tap.ini
>>> +++ b/doc/guides/nics/features/tap.ini
>>> @@ -14,10 +14,12 @@ Basic stats          = Y
>>>  L3 checksum offload  = Y
>>>  L4 checksum offload  = Y
>>>  MTU update           = Y
>>> +Multiprocess aware   = Y
>>>  
>>
>> ack
>>
>>>  Multicast MAC filter = Y
>>>  Unicast MAC filter   = Y
>>>  Packet type parsing  = Y
>>>  Flow control         = Y
>>> +Stats per queue      = Y
>>>  
>>
>> This feature name is misleading,
>> it is for 'rte_eth_dev_set_[rt]x_queue_stats_mapping()' API, which is
>> indeed for covering limitation for some drivers.
>> Tap does support getting stats per queue, but doesn't support above
>> documented feature.
> 
> The stats queue mapping was a feature that was hinted at being removed.
> It only exists because of HW limitations on Intel ixgbe NIC and SW
> limitations from RTE_ETHDEV_QUEUE_STAT_CNTRS.
> 


We have a plan to remove 'RTE_ETHDEV_QUEUE_STAT_CNTRS', by moving queue
stats to xstats.

But ixgbe limitation is there.

> Perhaps there should be a generic SW emulation for this the mapping?
>

Ack, cc'ed Bruce.
But I am not sure ROI of the effort at this stage.