[ovs-dev] [PATCH 1/2] ofproto-dpif: Rate limit facet_check_consistency()

[Ethan Jackson]

With complex flow tables, facet_check_consistency() can be
expensive enough to show up in flow setup performance benchmarks.
In my testing this patch gives us a roughly 10% improvement in
TCP_CRR and ovs-benchmark.

Signed-off-by: Ethan Jackson <ethan at nicira.com>
---
 ofproto/ofproto-dpif.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index b8db91d..30094f6 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -693,6 +693,7 @@ struct ofproto_dpif {
     struct hmap facets;
     struct hmap subfacets;
     struct governor *governor;
+    long long int consistency_rl;
 
     /* Revalidation. */
     struct table_dpif tables[N_TABLES];
@@ -1250,6 +1251,7 @@ construct(struct ofproto *ofproto_)
     hmap_init(&ofproto->facets);
     hmap_init(&ofproto->subfacets);
     ofproto->governor = NULL;
+    ofproto->consistency_rl = LLONG_MIN;
 
     for (i = 0; i < N_TABLES; i++) {
         struct table_dpif *table = &ofproto->tables[i];
@@ -1474,10 +1476,13 @@ run(struct ofproto *ofproto_)
     mac_learning_run(ofproto->ml, &ofproto->backer->revalidate_set);
 
     /* Check the consistency of a random facet, to aid debugging. */
-    if (!hmap_is_empty(&ofproto->facets)
+    if (time_msec() >= ofproto->consistency_rl
+        && !hmap_is_empty(&ofproto->facets)
         && !ofproto->backer->need_revalidate) {
         struct facet *facet;
 
+        ofproto->consistency_rl = time_msec() + 250;
+
         facet = CONTAINER_OF(hmap_random_node(&ofproto->facets),
                              struct facet, hmap_node);
         if (!tag_set_intersects(&ofproto->backer->revalidate_set,
-- 
1.7.9.5