Re: [dpdk-dev] [PATCH V2 1/4] ethdev: fix compiling errors for per-queue statistics

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

On 9/4/2020 12:32 PM, Min Hu (Connor) wrote:
> From: Huisong Li <lihuisong@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 driver and librte_ethdev
> during compiling dpdk project. But it is possible and permited 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.
> 
> Fixes: ed30d9b691b2 ("app/testpmd: add stats per queue")
> Fixes: 09c7e63a71f9 ("net/memif: introduce memory interface PMD")
> Fixes: abf7275bbaa2 ("ixgbe: move to drivers/net/")
> Fixes: e6defdfddc3b ("net/igc: enable statistics")
> Fixes: 2265e4b4e84b ("net/octeontx2: add basic stats operation")
> Fixes: 6c3169a3dc04 ("virtio: move to drivers/net/")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Huisong Li <lihuisong@huawei.com>
> Signed-off-by: Min Hu (Connor) <humin29@huawei.com>
> Reviewed-by: Wei Hu (Xavier) <xavier.huwei@huawei.com>
> Reviewed-by: Dongdong Liu <liudongdong3@huawei.com>

The patch mostly looks good and it enables build with
'RTE_ETHDEV_QUEUE_STAT_CNTRS' > 256.
Only I put a comment for a testpmd change to enable the "set stat_qmap" command
for map value > 256.


BUT there are many things to fix in the queue stats mapping, since you are
already on it can you help on a few things on testpmd related to it, if you have
time for it?

1) Getting queue stats shouldn't require stats mapping, it should be controlled
separately. Many PMDs doesn't require/do the stats mapping but they still can
collect the per queue stats, which can be displayed independent from mapping.

2) Even you map only one queue, while displaying stats it will display
'RTE_ETHDEV_QUEUE_STAT_CNTRS' queues, and when that number is high it makes hard
to see the actual interested values.
If there is no mapping, it should display min(number_of_queues,
RTE_ETHDEV_QUEUE_STAT_CNTRS).
If there is mapping it should display queues that mapping done, this may require
adding a new 'active' field to 'struct queue_stats_mappings'.

3) Why 'struct queue_stats_mappings' is cache aligned, is it really needed?

4) The mapping arrays, 'tx_queue_stats_mappings_array' &
'rx_queue_stats_mappings_array' are global and their size is based on fixed max
port and queue size assumptions, can those mapping array be done per port and
'RTE_ETHDEV_QUEUE_STAT_CNTRS' size per port?

Thanks,
ferruh