Re: [dpdk-dev] [RFC V4] app/testpmd: fix queue stats mapping configuration

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 11/20/2020 11:21 PM, Stephen Hemminger wrote:
> On Fri, 20 Nov 2020 17:26:55 +0000
> Ferruh Yigit <ferruh.yigit@intel.com> wrote:
> 
>> On 11/20/2020 11:50 AM, Min Hu (Connor) wrote:
>>> From: Huisong Li <lihuisong@huawei.com>
>>>
>>> Currently, the queue stats mapping has the following problems:
>>> 1) Many PMD drivers don't support queue stats mapping. But there is no
>>>    failure message after executing the command "set stat_qmap rx 0 2 2".
>>> 2) Once queue mapping is set, unrelated and unmapped queues are also
>>> displayed.
>>> 3) The configuration result does not take effect or can not be queried
>>> in real time.
>>> 4) The mapping arrays, "tx_queue_stats_mappings_array" &
>>> "rx_queue_stats_mappings_array" are global and their sizes are based on
>>> fixed max port and queue size assumptions.
>>> 5) These record structures, 'map_port_queue_stats_mapping_registers()'
>>>    and its sub functions are redundant for majority of drivers.
>>> 6) The display of the queue stats and queue stats mapping is mixed
>>>    together.
>>>
>>> Since xstats is used to obtain queue statistics, we have made the following
>>>    simplifications and adjustments:
>>> 1) If PMD requires and supports queue stats mapping, configure to driver in
>>>    real time by calling ethdev API after executing the command
>>>    "set stat_qmap rx/tx ...". If not, the command can not be accepted.
>>> 2) Based on the above adjustments, these record structures,
>>> 'map_port_queue_stats_mapping_registers()' and its sub functions can be
>>>    removed. "tx-queue-stats-mapping" & "rx-queue-stats-mapping" parameters,
>>>    and 'parse_queue_stats_mapping_config()' can be removed too.
>>> 3) remove display of queue stats mapping in 'fwd_stats_display()' &
>>>    'nic_stats_display()', and obtain queue stats by xstats.
>>>    Since the record structures are removed, 'nic_stats_mapping_display()'
>>>    can be deleted.
>>>
>>> Fixes: 4dccdc789bf4b ("app/testpmd: simplify handling of stats mappings error")
>>> Fixes: 013af9b6b64f6 ("app/testpmd: various updates")
>>> Fixes: ed30d9b691b21 ("app/testpmd: add stats per queue")
>>>
>>> Signed-off-by: Huisong Li <lihuisong@huawei.com>
>>
>> Overall	looks good to me.
>> I did a quick test didn't see anything unexpected. 'xstats' or 'dpdk-proc-info'
>> app still can be used to get queue stats and "set stat_qmap ..." is working as
>> expected.
>>
>> But it is a little late for this release cycle, would you be OK to get this at
>> the beginning of next release?
> 
> Could we plan to deprecate queue stats mapping in future when xstats work is done?
> 

Even queue stats moved to xstats, a few PMDs still need this configuration and API.
And this patch already cleans the queue stats mapping noise from testpmd.

What is the benefit/motivation to deprecate the queue stats mapping API?