[ovs-dev] [PATCH v2] ofproto-dpif-upcall: Log the emergency flow flush.

Flavio Leitner fbl at redhat.com
Tue Sep 29 20:07:46 UTC 2020


When the number of flows in the datapath reaches twice the
maximum, revalidators will delete all flows as an emergency
action to recover. In that case, log a message with values
and increase a coverage counter.

Signed-off-by: Flavio Leitner <fbl at redhat.com>
---
 ofproto/ofproto-dpif-upcall.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

v2:
  - updated the log message
  - print only once per cycle.

diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
index 195b01c13..35c240646 100644
--- a/ofproto/ofproto-dpif-upcall.c
+++ b/ofproto/ofproto-dpif-upcall.c
@@ -57,6 +57,7 @@ COVERAGE_DEFINE(upcall_ukey_contention);
 COVERAGE_DEFINE(upcall_ukey_replace);
 COVERAGE_DEFINE(revalidate_missed_dp_flow);
 COVERAGE_DEFINE(upcall_flow_limit_hit);
+COVERAGE_DEFINE(upcall_flow_limit_kill);
 
 /* A thread that reads upcalls from dpif, forwards each upcall's packet,
  * and possibly sets up a kernel flow as a cache. */
@@ -2607,6 +2608,7 @@ revalidate(struct revalidator *revalidator)
     struct udpif *udpif = revalidator->udpif;
     struct dpif_flow_dump_thread *dump_thread;
     uint64_t dump_seq, reval_seq;
+    bool kill_warn_print = true;
     unsigned int flow_limit;
 
     dump_seq = seq_read(udpif->dump_seq);
@@ -2623,6 +2625,7 @@ revalidate(struct revalidator *revalidator)
 
         long long int max_idle;
         long long int now;
+        size_t kill_all_limit;
         size_t n_dp_flows;
         bool kill_them_all;
 
@@ -2650,7 +2653,23 @@ revalidate(struct revalidator *revalidator)
             COVERAGE_INC(upcall_flow_limit_hit);
         }
 
-        kill_them_all = n_dp_flows > flow_limit * 2;
+        kill_them_all = false;
+        kill_all_limit = flow_limit * 2;
+        if (OVS_UNLIKELY(n_dp_flows > kill_all_limit)) {
+            static struct vlog_rate_limit rlem = VLOG_RATE_LIMIT_INIT(1, 1);
+
+            kill_them_all = true;
+            COVERAGE_INC(upcall_flow_limit_kill);
+            if (kill_warn_print) {
+                kill_warn_print = false;
+                VLOG_WARN_RL(&rlem, "Number of datapath flows (%"PRIuSIZE") "
+                             "twice as high as current dynamic flow limit (%"
+                             PRIuSIZE"). Starting to delete flows unconditionally"
+                             " as an emergency measure.", n_dp_flows,
+                             kill_all_limit);
+            }
+        }
+
         max_idle = n_dp_flows > flow_limit ? 100 : ofproto_max_idle;
 
         udpif->dpif->current_ms = time_msec();
-- 
2.26.2



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