Re: [dpdk-dev] [PATCH v3 1/2] net/failsafe: improve stats accuracy

["Gaëtan Rivet" <gaetan.rivet@6wind.com>]

Thanks Matan,

On Sat, Oct 21, 2017 at 08:54:45PM +0000, Matan Azrad wrote:
> The stats_get API was changed to signal a potential failure to read
> stats. Furthermore, some PMDs are able to provide statistics even
> after a removal event occurred.
> 
> Considering this, the fail-safe can try to access the latest
> statistics of a PMD to improve statistics accuracy.
> 
> Attempt an ultimate statistics read on removal time; if that
> fails, use the latest recorded snapshot.
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
Acked-by: Gaetan Rivet <gaetan.rivet@6wind.com>
> ---
>  drivers/net/failsafe/failsafe_ether.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> V2:
> Improve commit message.
> Add warning massage when using stats snapshot.
> Add time report from last snapshot.
> 
> V3:
> Separate patch.
> Replace "cycles" by "timestamp".
> 
> diff --git a/drivers/net/failsafe/failsafe_ether.c b/drivers/net/failsafe/failsafe_ether.c
> index f4db423..0282891 100644
> --- a/drivers/net/failsafe/failsafe_ether.c
> +++ b/drivers/net/failsafe/failsafe_ether.c
> @@ -312,8 +312,16 @@
>  static void
>  fs_dev_stats_save(struct sub_device *sdev)
>  {
> +	struct rte_eth_stats stats;
> +	int err;
> +
> +	/* Attempt to read current stats. */
> +	err = rte_eth_stats_get(PORT_ID(sdev), &stats);
> +	if (err)
> +		WARN("Could not access latest statistics from sub-device %d,"
> +			 " using latest snapshot.\n", SUB_ID(sdev));
>  	failsafe_stats_increment(&PRIV(sdev->fs_dev)->stats_accumulator,
> -			&sdev->stats_snapshot);
> +			err ? &sdev->stats_snapshot : &stats);
>  	memset(&sdev->stats_snapshot, 0, sizeof(struct rte_eth_stats));
>  }
>  
> -- 
> 1.8.3.1
> 

-- 
Gaëtan Rivet
6WIND