Re: [dpdk-dev] [PATCH v3 1/1] net/pcap: imissed stats support

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 2/3/2021 11:07 PM, Ido Goshen wrote:
> get value from pcap_stats.ps_drop (see man pcap_stats)
> the value is adjusted in this cases:
>   - port stop - pcap is closed and will lose count
>   - stats reset - pcap doesn't provide reset api
>   - rollover - pcap counter size is u_32 only
> 
> Signed-off-by: Ido Goshen <ido@cgstowernetworks.com>
> ---
> v3:
> * code cleanup by dedicated struct and functions extraction
> * multi stop support by menmonic+= accumulation
> * rollover fixup
> 
> v2:
> * sum all queues (rx_missed_total += fix)
> * null pcap protection
> * inter stop/start persistancy (counter won't reset on stop)
> 
>   drivers/net/pcap/rte_eth_pcap.c | 59 +++++++++++++++++++++++++++++++++
>   1 file changed, 59 insertions(+)
> 
> diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
> index a32b1f3f3..16e8752f3 100644
> --- a/drivers/net/pcap/rte_eth_pcap.c
> +++ b/drivers/net/pcap/rte_eth_pcap.c
> @@ -60,11 +60,21 @@ struct queue_stat {
>   	volatile unsigned long err_pkts;
>   };
>   
> +struct queue_missed_stat {
> +	/* last value retrieved from pcap */
> +	volatile unsigned int pcap;
> +	/* stores values lost by pcap stop or rollover */
> +	volatile unsigned long mnemonic;
> +	/* value on last reset */
> +	volatile unsigned long reset;
> +};

I am aware other stats has 'volatile' keyword, but as far as I can see it is not 
needed, since these are new ones can you please drop the 'volatile'?

> +
>   struct pcap_rx_queue {
>   	uint16_t port_id;
>   	uint16_t queue_id;
>   	struct rte_mempool *mb_pool;
>   	struct queue_stat rx_stat;
> +	struct queue_missed_stat missed_stat;
>   	char name[PATH_MAX];
>   	char type[ETH_PCAP_ARG_MAXLEN];
>   
> @@ -144,6 +154,49 @@ RTE_LOG_REGISTER(eth_pcap_logtype, pmd.net.pcap, NOTICE);
>   	rte_log(RTE_LOG_ ## level, eth_pcap_logtype, \
>   		"%s(): " fmt "\n", __func__, ##args)
>   
> +static struct queue_missed_stat*
> +queue_missed_stat_update(struct rte_eth_dev *dev, unsigned int qid)
> +{
> +	struct pmd_internals *internals = dev->data->dev_private;
> +	struct queue_missed_stat *missed_stat =
> +			&internals->rx_queue[qid].missed_stat;
> +	const struct pmd_process_private *pp = dev->process_private;
> +	pcap_t *pcap = pp->rx_pcap[qid];
> +	struct pcap_stat stat;

Can you please put an empty line after variable declarations, and before return.

> +	if (!pcap || (pcap_stats(pcap, &stat) != 0))
> +		return missed_stat;
> +	/* rollover check - best effort fixup assuming single rollover */
> +	if (stat.ps_drop < missed_stat->pcap)
> +		missed_stat->mnemonic += UINT_MAX;
> +	missed_stat->pcap = stat.ps_drop;

here.

> +	return missed_stat;
> +}
> +
> +static void
> +queue_missed_stat_on_stop_update(struct rte_eth_dev *dev, unsigned int qid)
> +{
> +	struct queue_missed_stat *missed_stat =
> +			queue_missed_stat_update(dev, qid);
> +	missed_stat->mnemonic += missed_stat->pcap;

Better to reset 'missed_stat->pcap' afterwards, in case stats requested before 
port started again:
  missed_stat->pcap = 0;

> +}
> +
> +static void
> +queue_missed_stat_reset(struct rte_eth_dev *dev, unsigned int qid)
> +{
> +	struct queue_missed_stat *missed_stat =
> +			queue_missed_stat_update(dev, qid);
> +	missed_stat->reset = missed_stat->pcap;

I guess this should be:
"missed_stat->reset = missed_stat->pcap + missed_stat->mnemonic;"

> +	missed_stat->mnemonic = 0;
> +}
> +
> +static unsigned long
> +queue_missed_stat_get(struct rte_eth_dev *dev, unsigned int qid)
> +{
> +	const struct queue_missed_stat *missed_stat =
> +			queue_missed_stat_update(dev, qid);
> +	return missed_stat->pcap + missed_stat->mnemonic - missed_stat->reset;
> +}
> +

<...>