[ovs-dev] [PATCH 3/4] ofproto-dpif: Don't poll ports when nothing changes

[Joe Stringer]

Currently, as part of ofproto-dpif run() processing, we loop through all
ports and poll corresponding devices for changes in carrier, cfm and bfd
status. This allows us to determine how it may affect bundles. For the
average case where devices are not going up or down constantly, this is
a large amount of unnecessary processing.

This patch gets the cfm, bfd and lacp modules to update the global
netdev change_seq when changes in port/device status occur. We can then
use this global change_seq to check if anything has changed before
looping through the ports in ofproto-dpif. In a test environment of 5000
internal ports and 50 tunnel ports with bfd, this reduces CPU usage from
about 35% to about 25%.

Signed-off-by: Joe Stringer <joestringer at nicira.com>
---
 lib/bfd.c              |    4 ++++
 lib/cfm.c              |    7 +++++++
 lib/lacp.c             |    3 +++
 ofproto/ofproto-dpif.c |    9 ++++++---
 4 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/lib/bfd.c b/lib/bfd.c
index 740f4fc..470d006 100644
--- a/lib/bfd.c
+++ b/lib/bfd.c
@@ -1019,6 +1019,8 @@ bfd_set_state(struct bfd *bfd, enum state state, enum diag diag)
         if (bfd->state == STATE_UP && bfd->decay_min_rx) {
             bfd_decay_update(bfd);
         }
+
+        netdev_notify_change();
     }
 }
 
@@ -1090,6 +1092,8 @@ bfd_forwarding_if_rx_update(struct bfd *bfd) OVS_REQUIRES(mutex)
 {
     int64_t incr = bfd_rx_interval(bfd) * bfd->mult;
     bfd->forwarding_if_rx_detect_time = MAX(incr, 2000) + time_msec();
+
+    netdev_notify_change();
 }
 
 static uint32_t
diff --git a/lib/cfm.c b/lib/cfm.c
index d256a5f..2dc9806 100644
--- a/lib/cfm.c
+++ b/lib/cfm.c
@@ -396,6 +396,7 @@ cfm_run(struct cfm *cfm) OVS_EXCLUDED(mutex)
         long long int interval = cfm_fault_interval(cfm);
         struct remote_mp *rmp, *rmp_next;
         bool old_cfm_fault = cfm->fault;
+        bool old_rmp_opup = cfm->remote_opup;
         bool demand_override;
         bool rmp_set_opup = false;
         bool rmp_set_opdown = false;
@@ -476,6 +477,10 @@ cfm_run(struct cfm *cfm) OVS_EXCLUDED(mutex)
             cfm->remote_opup = true;
         }
 
+        if (old_rmp_opup != cfm->remote_opup) {
+            netdev_notify_change();
+        }
+
         if (hmap_is_empty(&cfm->remote_mps)) {
             cfm->fault |= CFM_FAULT_RECV;
         }
@@ -495,6 +500,8 @@ cfm_run(struct cfm *cfm) OVS_EXCLUDED(mutex)
             if (old_cfm_fault == false || cfm->fault == false) {
                 cfm->flap_count++;
             }
+
+            netdev_notify_change();
         }
 
         cfm->booted = true;
diff --git a/lib/lacp.c b/lib/lacp.c
index 5421e2a..54e3111 100644
--- a/lib/lacp.c
+++ b/lib/lacp.c
@@ -21,6 +21,7 @@
 #include "dynamic-string.h"
 #include "hash.h"
 #include "hmap.h"
+#include "netdev.h"
 #include "ofpbuf.h"
 #include "packets.h"
 #include "poll-loop.h"
@@ -335,6 +336,7 @@ lacp_process_packet(struct lacp *lacp, const void *slave_,
     if (memcmp(&slave->partner, &pdu->actor, sizeof pdu->actor)) {
         lacp->update = true;
         slave->partner = pdu->actor;
+        netdev_notify_change();
     }
 
 out:
@@ -535,6 +537,7 @@ lacp_run(struct lacp *lacp, lacp_send_pdu *send_pdu) OVS_EXCLUDED(mutex)
                         : LACP_SLOW_TIME_TX);
 
             timer_set_duration(&slave->tx, duration);
+            netdev_notify_change();
         }
     }
     ovs_mutex_unlock(&mutex);
diff --git a/ofproto/ofproto-dpif.c b/ofproto/ofproto-dpif.c
index da27f6a..3717365 100644
--- a/ofproto/ofproto-dpif.c
+++ b/ofproto/ofproto-dpif.c
@@ -1470,7 +1470,6 @@ static int
 run(struct ofproto *ofproto_)
 {
     struct ofproto_dpif *ofproto = ofproto_dpif_cast(ofproto_);
-    struct ofport_dpif *ofport;
     struct ofbundle *bundle;
     int error;
 
@@ -1504,8 +1503,12 @@ run(struct ofproto *ofproto_)
         dpif_ipfix_run(ofproto->ipfix);
     }
 
-    HMAP_FOR_EACH (ofport, up.hmap_node, &ofproto->up.ports) {
-        port_run(ofport);
+    if (netdev_changed(ofproto_->change_seq)) {
+        struct ofport_dpif *ofport;
+
+        HMAP_FOR_EACH (ofport, up.hmap_node, &ofproto->up.ports) {
+            port_run(ofport);
+        }
     }
     HMAP_FOR_EACH (bundle, hmap_node, &ofproto->bundles) {
         bundle_run(bundle);
-- 
1.7.9.5