Re: [dpdk-dev] [PATCH 1/4] e1000: remove crc size from all byte counters

[Stephen Hemminger <shemming@brocade.com>]

On Mon, 16 Nov 2015 10:35:14 +0000
Harry van Haaren <harry.van.haaren@intel.com> wrote:

> This patch removes the crc bytes from byte counter statistics.
> 
> Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
> ---
>  drivers/net/e1000/igb_ethdev.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/e1000/igb_ethdev.c b/drivers/net/e1000/igb_ethdev.c
> index 88995b0..0ad7341 100644
> --- a/drivers/net/e1000/igb_ethdev.c
> +++ b/drivers/net/e1000/igb_ethdev.c
> @@ -1480,6 +1480,13 @@ igb_read_stats_registers(struct e1000_hw *hw, struct e1000_hw_stats *stats)
>  {
>  	int pause_frames;
>  
> +	uint64_t old_gprc  = stats->gprc;
> +	uint64_t old_gptc  = stats->gptc;
> +	uint64_t old_tpr   = stats->tpr;
> +	uint64_t old_tpt   = stats->tpt;
> +	uint64_t old_rpthc = stats->rpthc;
> +	uint64_t old_hgptc = stats->hgptc;
> +
>  	if(hw->phy.media_type == e1000_media_type_copper ||
>  	    (E1000_READ_REG(hw, E1000_STATUS) & E1000_STATUS_LU)) {
>  		stats->symerrs +=
> @@ -1521,10 +1528,13 @@ igb_read_stats_registers(struct e1000_hw *hw, struct e1000_hw_stats *stats)
>  	/* For the 64-bit byte counters the low dword must be read first. */
>  	/* Both registers clear on the read of the high dword */
>  
> +	/* Workaround CRC bytes included in size, take away 4 bytes/packet */
>  	stats->gorc += E1000_READ_REG(hw, E1000_GORCL);
>  	stats->gorc += ((uint64_t)E1000_READ_REG(hw, E1000_GORCH) << 32);
> +	stats->gorc -= (stats->gprc - old_gprc) * 4;
>  	stats->gotc += E1000_READ_REG(hw, E1000_GOTCL);
>  	stats->gotc += ((uint64_t)E1000_READ_REG(hw, E1000_GOTCH) << 32);
> +	stats->gotc -= (stats->gptc - old_gptc) * 4;
>  
>  	stats->rnbc += E1000_READ_REG(hw, E1000_RNBC);
>  	stats->ruc += E1000_READ_REG(hw, E1000_RUC);
> @@ -1532,13 +1542,16 @@ igb_read_stats_registers(struct e1000_hw *hw, struct e1000_hw_stats *stats)
>  	stats->roc += E1000_READ_REG(hw, E1000_ROC);
>  	stats->rjc += E1000_READ_REG(hw, E1000_RJC);
>  
> +	stats->tpr += E1000_READ_REG(hw, E1000_TPR);
> +	stats->tpt += E1000_READ_REG(hw, E1000_TPT);
> +
>  	stats->tor += E1000_READ_REG(hw, E1000_TORL);
>  	stats->tor += ((uint64_t)E1000_READ_REG(hw, E1000_TORH) << 32);
> +	stats->tor -= (stats->tpr - old_tpr) * 4;

Why not use ETHER_CRC_LEN rather than magic # 4?