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

[Kevin Traynor]

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
+};
+
 #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'. */
 };
 
@@ -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);
-
 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);
@@ -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