[ovs-dev] [PATCH v5 2/6] dpif-netdev: Add rxq processing cycle counters.

[Darrell Ball]

    On 8/23/17, 6:34 AM, "Kevin Traynor" <ktraynor at redhat.com> wrote:
    
        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 | 28 +++++++++++++++++++++++++---
         1 file changed, 25 insertions(+), 3 deletions(-)
        
        diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
        index f35c079..51d4050 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
        +};
        +
         #define XPS_TIMEOUT_MS 500LL
         
        @@ -351,4 +364,9 @@ struct dp_netdev_rxq {
                                                   particular core. */
             struct dp_netdev_pmd_thread *pmd;  /* pmd thread that polls this queue. */
        +
        +    /* Counters of cycles spent polling and processing packets. */

Do we need to specify ‘successfully’ polling to avoid confusion ?

        +    atomic_ullong cycles[RXQ_N_CYCLES];

Do you think below deserves a separate description – ‘we store the last PMD_RXQ_INTERVAL_MAX  intervals and sum them up to 
to yield the cycles used for a given rxq…’ ?

        +    atomic_ullong cycles_intrvl[PMD_RXQ_INTERVAL_MAX];
        +    unsigned intrvl_idx;               /* Write index for 'cycles_intrvl'. */
         };
         
        @@ -677,5 +695,4 @@ 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);
        -
         static void
         dpif_netdev_xps_revalidate_pmd(const struct dp_netdev_pmd_thread *pmd,
        @@ -3092,4 +3109,5 @@ 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 +3118,8 @@ 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 +3690,5 @@ 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);
        @@ -3855,5 +3877,5 @@ 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