[ovs-dev] [PATCH v6 2/6] dpif-netdev: Add rxq processing cycle counters.

[Ilya Maximets]

> Add counters to dp_netdev_rxq which will later be used for storing the
> processing cycles of an rxq. Processing cycles will be stored in reference
> to a defined time interval. We will store the cycles of the current in progress
> interval, a number of completed intervals and the sum of the completed
> intervals.
> 
> cycles_count_intermediate was used to count cycles for a pmd. With some small
> additions we can also use it to count the cycles used for processing an rxq.
> 
> Signed-off-by: Kevin Traynor <ktraynor at redhat.com>
> ---
>  lib/dpif-netdev.c | 30 +++++++++++++++++++++++++++---
>  1 file changed, 27 insertions(+), 3 deletions(-)
> 
> diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
> index f35c079..8731435 100644
> --- a/lib/dpif-netdev.c
> +++ b/lib/dpif-netdev.c
> @@ -182,4 +182,8 @@ struct emc_cache {
>  #define DPCLS_OPTIMIZATION_INTERVAL 1000
>  
> +/* Number of intervals for which cycles are stored
> + * and used during rxq to pmd assignment. */
> +#define PMD_RXQ_INTERVAL_MAX 6
> +
>  struct dpcls {
>      struct cmap_node node;      /* Within dp_netdev_pmd_thread.classifiers */
> @@ -340,4 +344,13 @@ enum pmd_cycles_counter_type {
>  };
>  
> +enum rxq_cycles_counter_type {
> +    RXQ_CYCLES_PROC_CURR,       /* Cycles spent successfully polling and
> +                                   processing packets during the current
> +                                   interval. */
> +    RXQ_CYCLES_PROC_HIST,       /* Total cycles of all intervals that are used
> +                                   during rxq to pmd assignment. */
> +    RXQ_N_CYCLES
> +};

All patches wide: Multi-line comments should have a '*' on each line.

> +
>  #define XPS_TIMEOUT_MS 500LL
>  
> @@ -351,4 +364,11 @@ struct dp_netdev_rxq {
>                                            particular core. */
>      struct dp_netdev_pmd_thread *pmd;  /* pmd thread that polls this queue. */
> +
> +    /* Counters of cycles spent successfully polling and processing pkts. */
> +    atomic_ullong cycles[RXQ_N_CYCLES];
> +    /* We store PMD_RXQ_INTERVAL_MAX intervals of data for an rxq and then
> +       sum them to yield the cycles used for an rxq. */
> +    atomic_ullong cycles_intrvl[PMD_RXQ_INTERVAL_MAX];
> +    unsigned intrvl_idx;               /* Write index for 'cycles_intrvl'. */

Does it matter to save 2 letters in a variable names? It looks ugly and unreadable.

>  };
>  
> @@ -677,5 +697,4 @@ static void pmd_load_cached_ports(struct dp_netdev_pmd_thread *pmd)
>  static inline void
>  dp_netdev_pmd_try_optimize(struct dp_netdev_pmd_thread *pmd);
> -

Is it necessary to remove this line? It was here to split xps related functions
from others.

>  static void
>  dpif_netdev_xps_revalidate_pmd(const struct dp_netdev_pmd_thread *pmd,
> @@ -3092,4 +3111,5 @@ cycles_count_end(struct dp_netdev_pmd_thread *pmd,
>  static inline void
>  cycles_count_intermediate(struct dp_netdev_pmd_thread *pmd,
> +                          struct dp_netdev_rxq *rxq,
>                            enum pmd_cycles_counter_type type)
>      OVS_NO_THREAD_SAFETY_ANALYSIS
> @@ -3100,4 +3120,8 @@ cycles_count_intermediate(struct dp_netdev_pmd_thread *pmd,
>  
>      non_atomic_ullong_add(&pmd->cycles.n[type], interval);
> +    if (rxq && (type == PMD_CYCLES_PROCESSING)) {
> +        /* Add to the amount of current processing cycles. */
> +        non_atomic_ullong_add(&rxq->cycles[RXQ_CYCLES_PROC_CURR], interval);
> +    }
>  }
>  
> @@ -3668,5 +3692,5 @@ dpif_netdev_run(struct dpif *dpif)
>                                                     port->rxqs[i].rx,
>                                                     port->port_no);
> -                    cycles_count_intermediate(non_pmd, process_packets ?
> +                    cycles_count_intermediate(non_pmd, NULL, process_packets ?
>                                                         PMD_CYCLES_PROCESSING
>                                                       : PMD_CYCLES_IDLE);

It's not yours, but it'll be nice to fix here:
According to coding style, '?' should be on the next line near to arguments.
Also, IMHO, the whole construction should have the same level of indention.

Like this:
                    cycles_count_intermediate(non_pmd, NULL,
                                              process_packets
                                              ? PMD_CYCLES_PROCESSING
                                              : PMD_CYCLES_IDLE);
Or this:
                     cycles_count_intermediate(                                                                                  
                         non_pmd, NULL, process_packets ? PMD_CYCLES_PROCESSING 
                                                        : PMD_CYCLES_IDLE);

> @@ -3855,5 +3879,5 @@ reload:
>                  dp_netdev_process_rxq_port(pmd, poll_list[i].rxq->rx,
>                                             poll_list[i].port_no);
> -            cycles_count_intermediate(pmd,
> +            cycles_count_intermediate(pmd, NULL,
>                                        process_packets ? PMD_CYCLES_PROCESSING
>                                                        : PMD_CYCLES_IDLE);
> -- 
> 1.8.3.1