Re: [dpdk-dev] [PATCH v3] net/ixgbe: include QPRDC in imissed stat

["Zhao1, Wei" <wei.zhao1@intel.com>]

HI，Cody Harris

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Cody Harris
> Sent: Tuesday, May 19, 2020 1:08 PM
> To: dev@dpdk.org
> Cc: Cody Harris <codh@amazon.com>
> Subject: [dpdk-dev] [PATCH v3] net/ixgbe: include QPRDC in imissed stat
> 
> The ixgbe imissed statstic originally only contained dropped packets counted by
> the RXMPC registers. This change includes additional types of packet drops
> counted by the QPRDC registers.
> 
> Intel support confimed that the packet drops counted by the QPRDC registers
> do not double-count drops counted by RXMPC registers:
> 
> "RXMPC counts packets that are dropped because there is no room in the
> internal packet buffer.  QPRDC counts packets that are dropped because they
> can't be transferred to system memory. These packets have been stored in the
> internal packet buffer, so there should be no overlap with RXMPC."
> 
> Signed-off-by: Cody Harris <codh@amazon.com>
> ---
>  drivers/net/ixgbe/ixgbe_ethdev.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ixgbe/ixgbe_ethdev.c
> b/drivers/net/ixgbe/ixgbe_ethdev.c
> index a4e5c539d..7284ca28e 100644
> --- a/drivers/net/ixgbe/ixgbe_ethdev.c
> +++ b/drivers/net/ixgbe/ixgbe_ethdev.c
> @@ -3366,7 +3366,7 @@ ixgbe_dev_stats_get(struct rte_eth_dev *dev,
> struct rte_eth_stats *stats)
>  	}
> 
>  	/* Rx Errors */
> -	stats->imissed  = total_missed_rx;
> +	stats->imissed  = total_missed_rx + total_qprdc;

If Rx queue is disabled in the RXDCTL register, packet direct to this queue is also dropped and count by this 
Register QPRDC, but the definition of imissed is "Total of RX packets dropped by the HW because there are no available buffer" in rte layer.
So, it maybe mislead users if we mix the 2 statistic, is that so?
Also, x550 has other definition for this register, we can not mix them.


>  	stats->ierrors  = hw_stats->crcerrs +
>  			  hw_stats->mspdc +
>  			  hw_stats->rlec +
> --
> 2.24.1.AMZN