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

[Kevin Traynor <ktraynor@redhat.com>]

On 28/09/2021 03:12, Zhang, AlvinX wrote:
>> -----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.
> 

Hi Alvin. Thanks for answering my questions and showing how it was 
tested. I don't have any more comments. I won't ack just because I am 
not familiar enough with the i40e stats in general to give a meaningful ack.

Kevin.

>>
>> 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;
>>>
>