bridge: Fix high cpu utilization.

When there are more than one ovs-vswitchd processes started,
only one process is enabled.  The disabled processes should
just sleep.  However, a bug in ovs makes the disabled processes
keep waking up on global connectivity sequence number which is
never sync'ed.  Consequently, those processes use 100% cpu.

This commit fixes the bug by always sync up the connectivity
sequence number for disabled processes.

Reported-by: Ben Pfaff <blp@nicira.com>
Signed-off-by: Alex Wang <alexw@nicira.com>
Acked-by: Joe Stringer <joestringer@nicira.com>

diff --git a/tests/ovs-vswitchd.at b/tests/ovs-vswitchd.at
index cbe0ee9..71a2b40 100644 (file)
--- a/tests/ovs-vswitchd.at
+++ b/tests/ovs-vswitchd.at
@@ -66,3 +66,40 @@ OVS_VSCTL_CHECK_RX_PKT([p1], [7])
 
 OVS_VSWITCHD_STOP
 AT_CLEANUP
+
+dnl ----------------------------------------------------------------------
+AT_SETUP([ovs-vswitchd -- start additional ovs-vswitchd process])
+OVS_VSWITCHD_START
+
+# start another ovs-vswitchd process.
+ovs-vswitchd --log-file=fakelog &
+pid=`echo $!`
+
+# sleep for a while
+sleep 5
+
+# stop the process.
+kill $pid
+
+# check the fakelog, should only see one ERR for reporting
+# the existing ovs-vswitchd process and one WARN for killing
+# the process.
+AT_CHECK([grep ERR fakelog | wc -l], [0], [dnl
+1
+])
+
+AT_CHECK([grep WARN fakelog | wc -l], [0], [dnl
+1
+])
+
+AT_CHECK([grep ERR fakelog | sed -e 's/^.*ERR|//; s/pid [[0-9]]*//'], [0], [dnl
+another ovs-vswitchd process is running, disabling this process () until it goes away
+])
+
+# check the fakelog, the ERR log should be the last line.
+AT_CHECK([tail -n 2 fakelog | head -n 1 | sed -e 's/^.*ERR|//; s/pid [[0-9]]*//'], [0], [dnl
+another ovs-vswitchd process is running, disabling this process () until it goes away
+])
+
+OVS_VSWITCHD_STOP
+AT_CLEANUP

diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index 822b471..69d4396 100644 (file)
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -2311,6 +2311,9 @@ bridge_run(void)
          * with the current situation of multiple ovs-vswitchd daemons,
          * disable system stats collection. */
         system_stats_enable(false);
+        /* This prevents the process from constantly waking up on
+         * connectivity seq. */
+        connectivity_seqno = seq_read(connectivity_seq_get());
         return;
     } else if (!ovsdb_idl_has_lock(idl)) {
         return;