Re: [dpdk-dev] [PATCH] net/i40e: fix Rx packet statistics

["Zhang, AlvinX" <alvinx.zhang@intel.com>]

> -----Original Message-----
> From: Kevin Traynor <ktraynor@redhat.com>
> Sent: Tuesday, September 28, 2021 12:00 AM
> To: Zhang, AlvinX <alvinx.zhang@intel.com>; Xing, Beilei
> <beilei.xing@intel.com>; Guo, Junfeng <junfeng.guo@intel.com>
> Cc: dev@dpdk.org; stable@dpdk.org; Zhang, Qi Z <qi.z.zhang@intel.com>;
> Yigit, Ferruh <ferruh.yigit@intel.com>
> Subject: Re: [dpdk-dev] [PATCH] net/i40e: fix Rx packet statistics
> 
> On 26/09/2021 08:57, Alvin Zhang wrote:
> > Some packets are discarded by the NIC because they are larger than the
> > MTU, these packets should be counted as "RX error" instead of "RX
> > packet".
> >
> > The register 'GL_RXERR1' can count above discarded packets.
> > This patch adds reading and calculation of the 'GL_RXERR1' counter
> > when reporting DPDK statistics.
> >
> > Fixes: f4a91c38b4ad ("i40e: add extended stats")
> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Alvin Zhang <alvinx.zhang@intel.com>
> > ---
> >   drivers/net/i40e/i40e_ethdev.c | 16 +++++++++++++---
> >   drivers/net/i40e/i40e_ethdev.h | 10 ++++++++++
> >   2 files changed, 23 insertions(+), 3 deletions(-)
> >
> 
> It's a bit hard to understand the code for someone not familiar with the i40e
> stats. I think it needs careful review from i40e maintainers. A few questions
> below,
> 
> Did you test this with testpmd? Can you show an example of a test where these
> packets are now correctly accounted for?

The issue as below:

sendp(Ether()/IP()/Raw('x' * 1500), iface="enp24s0f1")
---------------------- Forward statistics for port 0 ----------------------
RX-packets: 1 RX-dropped: 0 RX-total: 1
TX-packets: 0 TX-dropped: 0 TX-total: 0
----------------------------------------------------------------------------

Although we didn't really got the packet, but the statistic indicates a packet has been received successfully.
We can add above example to commit log in V2.

> 
> I see there is also an RXERR2 register that catches other errors, does it need to
> be considered as well?

We are not sure whether the packets counted by RXERR2 also will be counted by "Rx-packets".
So in this patch we only consider RXERR1 and fix the issue mentioned above.

> 
> > diff --git a/drivers/net/i40e/i40e_ethdev.c
> > b/drivers/net/i40e/i40e_ethdev.c index 7a2a828..30a2cdf 100644
> > --- a/drivers/net/i40e/i40e_ethdev.c
> > +++ b/drivers/net/i40e/i40e_ethdev.c
> > @@ -532,7 +532,7 @@ static int i40e_sw_tunnel_filter_insert(struct i40e_pf
> *pf,
> >   /* store statistics names and its offset in stats structure */
> >   struct rte_i40e_xstats_name_off {
> >   	char name[RTE_ETH_XSTATS_NAME_SIZE];
> > -	unsigned offset;
> > +	int offset;
> 
> It is unusual to see you changing an offset to an int. You are expecting negative
> offsets?
> 
> >   };
> >
> >   static const struct rte_i40e_xstats_name_off
> > rte_i40e_stats_strings[] = { @@ -542,6 +542,8 @@ struct
> rte_i40e_xstats_name_off {
> >   	{"rx_dropped_packets", offsetof(struct i40e_eth_stats, rx_discards)},
> >   	{"rx_unknown_protocol_packets", offsetof(struct i40e_eth_stats,
> >   		rx_unknown_protocol)},
> > +	{"rx_err1", offsetof(struct i40e_pf, rx_err1) -
> > +		    offsetof(struct i40e_pf, stats)},

Here offsetof(struct i40e_pf, rx_err1) - offsetof(struct i40e_pf, stats) may be a negative value.

> 
> rx_err1 is correct by datasheet but meaningless to a user. Suggest to find a more
> descriptive name, or document what it is, or tell the user to reference the
> datasheet.

I will update it in v2.

> 
> >   	{"tx_unicast_packets", offsetof(struct i40e_eth_stats, tx_unicast)},
> >   	{"tx_multicast_packets", offsetof(struct i40e_eth_stats,
> tx_multicast)},
> >   	{"tx_broadcast_packets", offsetof(struct i40e_eth_stats,
> > tx_broadcast)}, @@ -3238,6 +3240,10 @@ void
> i40e_flex_payload_reg_set_default(struct i40e_hw *hw)
> >   			    pf->offset_loaded,
> >   			    &os->eth.rx_unknown_protocol,
> >   			    &ns->eth.rx_unknown_protocol);
> > +	i40e_stat_update_48(hw, I40E_GL_RXERR1_H(hw->pf_id +
> I40E_MAX_VF),
> > +			    I40E_GL_RXERR1_L(hw->pf_id + I40E_MAX_VF),
> > +			    pf->offset_loaded, &pf->rx_err1_offset,
> > +			    &pf->rx_err1);
> >   	i40e_stat_update_48_in_64(hw, I40E_GLPRT_GOTCH(hw->port),
> >   				  I40E_GLPRT_GOTCL(hw->port),
> >   				  pf->offset_loaded, &os->eth.tx_bytes, @@ -3437,7
> +3443,8 @@
> > void i40e_flex_payload_reg_set_default(struct i40e_hw *hw)
> >   	stats->ipackets = pf->main_vsi->eth_stats.rx_unicast +
> >   			pf->main_vsi->eth_stats.rx_multicast +
> >   			pf->main_vsi->eth_stats.rx_broadcast -
> > -			pf->main_vsi->eth_stats.rx_discards;
> > +			pf->main_vsi->eth_stats.rx_discards -
> > +			pf->rx_err1;
> >   	stats->opackets = ns->eth.tx_unicast +
> >   			ns->eth.tx_multicast +
> >   			ns->eth.tx_broadcast;
> > @@ -3451,7 +3458,8 @@ void i40e_flex_payload_reg_set_default(struct
> i40e_hw *hw)
> >   			pf->main_vsi->eth_stats.rx_discards;
> >   	stats->ierrors  = ns->crc_errors +
> >   			ns->rx_length_errors + ns->rx_undersize +
> > -			ns->rx_oversize + ns->rx_fragments + ns->rx_jabber;
> > +			ns->rx_oversize + ns->rx_fragments + ns->rx_jabber +
> > +			pf->rx_err1;
> >
> >   	if (pf->vfs) {
> >   		for (i = 0; i < pf->vf_num; i++) { @@ -6232,6 +6240,8 @@ struct
> > i40e_vsi *
> >   	memset(&pf->stats_offset, 0, sizeof(struct i40e_hw_port_stats));
> >   	memset(&pf->internal_stats, 0, sizeof(struct i40e_eth_stats));
> >   	memset(&pf->internal_stats_offset, 0, sizeof(struct
> > i40e_eth_stats));
> > +	pf->rx_err1 = 0;
> > +	pf->rx_err1_offset = 0;
> >
> >   	ret = i40e_pf_get_switch_config(pf);
> >   	if (ret != I40E_SUCCESS) {
> > diff --git a/drivers/net/i40e/i40e_ethdev.h
> > b/drivers/net/i40e/i40e_ethdev.h index cd6deab..846c8d4 100644
> > --- a/drivers/net/i40e/i40e_ethdev.h
> > +++ b/drivers/net/i40e/i40e_ethdev.h
> > @@ -19,6 +19,13 @@
> >   #include "base/i40e_type.h"
> >   #include "base/virtchnl.h"
> >
> > +#define I40E_GL_RXERR1_H(_i)	(0x00318004 + ((_i) * 8))
> > +/**
> > + * _i=0...143,
> > + * counters 0-127 are for the 128 VFs,
> > + * counters 128-143 are for the 16 PFs  */
> > +
> >   #define I40E_VLAN_TAG_SIZE        4
> >
> >   #define I40E_AQ_LEN               32
> > @@ -1134,6 +1141,9 @@ struct i40e_pf {
> >
> >   	struct i40e_hw_port_stats stats_offset;
> >   	struct i40e_hw_port_stats stats;
> > +	u64 rx_err1;	/* rxerr1 */
> > +	u64 rx_err1_offset;
> > +
> >   	/* internal packet statistics, it should be excluded from the total */
> >   	struct i40e_eth_stats internal_stats_offset;
> >   	struct i40e_eth_stats internal_stats;
> >