[ovs-dev,v4,3/3] dpif-netdev: Calculate rxq cycles prior to compare_rxq_cycles calls.

Message ID 1511466117-27191-3-git-send-email-ktraynor@redhat.com
State New
Delegated to: Ian Stokes
Headers show
Series
  • [ovs-dev,v4,1/3] dpif-netdev: Add port/queue tiebreaker to rxq_cycle_sort.
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Commit Message

Kevin Traynor Nov. 23, 2017, 7:41 p.m.
compare_rxq_cycles sums the latest cycles from each queue for
comparison with each other. While each comparison correctly
gets the latest cycles, the cycles could change between calls
to compare_rxq_cycle. In order to use consistent values through
each call of compare_rxq_cycles, sum the cycles before qsort is
called.

Requested-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Kevin Traynor <ktraynor@redhat.com>
---
V4: Rebased to apply after patches 1/3 and 2/3

V3:
- Drop V2 1/2 as merged
- Removed rxq_cycle_sort return changes for a later patch
- Some minor variable rename and comment changes


 lib/dpif-netdev.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

Patch

diff --git a/lib/dpif-netdev.c b/lib/dpif-netdev.c
index 657df71..c31c09e 100644
--- a/lib/dpif-netdev.c
+++ b/lib/dpif-netdev.c
@@ -3450,20 +3450,14 @@  compare_rxq_cycles(const void *a, const void *b)
     struct dp_netdev_rxq *qa;
     struct dp_netdev_rxq *qb;
-    uint64_t total_qa, total_qb;
-    unsigned i;
+    uint64_t cycles_qa, cycles_qb;
 
     qa = *(struct dp_netdev_rxq **) a;
     qb = *(struct dp_netdev_rxq **) b;
 
-    total_qa = total_qb = 0;
-    for (i = 0; i < PMD_RXQ_INTERVAL_MAX; i++) {
-        total_qa += dp_netdev_rxq_get_intrvl_cycles(qa, i);
-        total_qb += dp_netdev_rxq_get_intrvl_cycles(qb, i);
-    }
-    dp_netdev_rxq_set_cycles(qa, RXQ_CYCLES_PROC_HIST, total_qa);
-    dp_netdev_rxq_set_cycles(qb, RXQ_CYCLES_PROC_HIST, total_qb);
+    cycles_qa = dp_netdev_rxq_get_cycles(qa, RXQ_CYCLES_PROC_HIST);
+    cycles_qb = dp_netdev_rxq_get_cycles(qb, RXQ_CYCLES_PROC_HIST);
 
-    if (total_qa != total_qb) {
-        return (total_qa < total_qb) ? 1 : -1;
+    if (cycles_qa != cycles_qb) {
+        return (cycles_qa < cycles_qb) ? 1 : -1;
     } else {
         /* Cycles are the same so tiebreak on port/queue id.
@@ -3521,4 +3515,6 @@  rxq_scheduling(struct dp_netdev *dp, bool pinned) OVS_REQUIRES(dp->port_mutex)
                 }
             } else if (!pinned && q->core_id == OVS_CORE_UNSPEC) {
+                uint64_t cycle_hist = 0;
+
                 if (n_rxqs == 0) {
                     rxqs = xmalloc(sizeof *rxqs);
@@ -3526,4 +3522,10 @@  rxq_scheduling(struct dp_netdev *dp, bool pinned) OVS_REQUIRES(dp->port_mutex)
                     rxqs = xrealloc(rxqs, sizeof *rxqs * (n_rxqs + 1));
                 }
+                /* Sum the queue intervals and store the cycle history. */
+                for (unsigned i = 0; i < PMD_RXQ_INTERVAL_MAX; i++) {
+                    cycle_hist += dp_netdev_rxq_get_intrvl_cycles(q, i);
+                }
+                dp_netdev_rxq_set_cycles(q, RXQ_CYCLES_PROC_HIST, cycle_hist);
+
                 /* Store the queue. */
                 rxqs[n_rxqs++] = q;