[dpdk-dev] [dpdk-techboard] [PATCH V5 1/2] dpdk: resolve compiling errors for per-queue stats

[Ananyev, Konstantin]

> 28/09/2020 10:59, Ferruh Yigit:
> > On 9/27/2020 4:16 AM, Min Hu (Connor) wrote:
> > > From: Huisong Li <lihuisong at huawei.com>
> > >
> > > Currently, only statistics of rx/tx queues with queue_id less than
> > > RTE_ETHDEV_QUEUE_STAT_CNTRS can be displayed. If there is a certain
> > > application scenario that it needs to use 256 or more than 256 queues
> > > and display all statistics of rx/tx queue. At this moment, we have to
> > > change the macro to be equaled to the queue number.
> > >
> > > However, modifying the macro to be greater than 256 will trigger
> > > many errors and warnings from test-pmd, PMD drivers and librte_ethdev
> > > during compiling dpdk project. But it is possible and permitted that
> > > rx/tx queue number is greater than 256 and all statistics of rx/tx
> > > queue need to be displayed. In addition, the data type of rx/tx queue
> > > number in rte_eth_dev_configure API is 'uint16_t'. So It is unreasonable
> > > to use the 'uint8_t' type for variables that control which per-queue
> > > statistics can be displayed.
> 
> The explanation is too much complex and misleading.
> You mean you cannot increase RTE_ETHDEV_QUEUE_STAT_CNTRS
> above 256 because it is an 8-bit type?
> 
> [...]
> > > --- a/lib/librte_ethdev/rte_ethdev.h
> > > +++ b/lib/librte_ethdev/rte_ethdev.h
> > >   int rte_eth_dev_set_tx_queue_stats_mapping(uint16_t port_id,
> > > -		uint16_t tx_queue_id, uint8_t stat_idx);
> > > +		uint16_t tx_queue_id, uint16_t stat_idx);
> [...]
> > >   int rte_eth_dev_set_rx_queue_stats_mapping(uint16_t port_id,
> > >   					   uint16_t rx_queue_id,
> > > -					   uint8_t stat_idx);
> > > +					   uint16_t stat_idx);
> [...]
> > cc'ed tech-board,
> >
> > The patch breaks the ethdev ABI without a deprecation notice from previous
> > release(s).
> >
> > It is mainly a fix to the port_id storage type, which we have updated from
> > uint8_t to uint16_t in past but some seems remained for
> > 'rte_eth_dev_set_tx_queue_stats_mapping()' &
> > 'rte_eth_dev_set_rx_queue_stats_mapping()' APIs.
> 
> No, it is not related to the port id, but the number of limited stats.it
> it is not limited. In this case, we probably don't need the API
> *_queue_stats_mapping which was invented for a limitation of ixgbe.

It is probably a bit unusual specially for modern NICs,
but I think it still possible in principle.
Let say NIC has up to 16K queues, but can map stats only for 1K, or so.
So formally - yes, I think both queue_idx and stats_idx have to be same type.
Also I can't foresee problems such change could introduce (except formal API/ABI break).
So:
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>

> 
> The problem is probably somewhere else (in testpmd),
> that's why I am against this patch.
>