Fix a problem with high CPU consumption (up to 30%) by bsnmpd on a loaded system.

Instead of constantly calling the mibII_idle function when the server is not busy
call the function only once every 10 seconds to avoid bsnmpd constantly doing
gettimeofday syscalls. Make the idle polling interval confugurable via
begemotIfDataPoll.

Reported and tested by: misho (at) aitbg (dot) com
Oked by: harti
MFC after:	1 week

1 files changed, 34 insertions, 2 deletions

diff --git a/contrib/bsnmp/snmp_mibII/mibII.c b/contrib/bsnmp/snmp_mibII/mibII.c
index cd4caac..8714695 100644
--- a/contrib/bsnmp/snmp_mibII/mibII.c
+++ b/contrib/bsnmp/snmp_mibII/mibII.c
@@ -117,6 +117,15 @@ u_int mibif_hc_update_interval;
 /* HC update timer handle */
 static void *hc_update_timer;
 
+/* Idle poll timer */
+static void *mibII_poll_timer;
+
+/* interfaces' data poll interval */
+u_int mibII_poll_ticks;
+
+/* Idle poll hook */
+static void mibII_idle(void *arg __unused);
+
 /*****************************/
 
 static const struct asn_oid oid_ifMIB = OIDX_ifMIB;
@@ -410,6 +419,20 @@ mibif_reset_hc_timer(void)
 	mibif_hc_update_interval = ticks;
 }
 
+/**
+ * Restart the idle poll timer.
+ */
+void
+mibif_restart_mibII_poll_timer(void)
+{
+	if (mibII_poll_timer != NULL)
+		timer_stop(mibII_poll_timer);
+
+	if ((mibII_poll_timer = timer_start_repeat(mibII_poll_ticks * 10,
+	    mibII_poll_ticks * 10, mibII_idle, NULL, module)) == NULL)
+		syslog(LOG_ERR, "timer_start(%u): %m", mibII_poll_ticks);
+}
+
 /*
  * Fetch new MIB data.
  */
@@ -1553,7 +1576,7 @@ get_cloners(void)
  * Idle function
  */
 static void
-mibII_idle(void)
+mibII_idle(void *arg __unused)
 {
 	struct mibifa *ifa;
 
@@ -1608,6 +1631,10 @@ mibII_start(void)
 	ipForward_reg = or_register(&oid_ipForward,
 	   "The MIB module for the display of CIDR multipath IP Routes.",
 	   module);
+
+	mibII_poll_timer = NULL;
+	mibII_poll_ticks = MIBII_POLL_TICKS;
+	mibif_restart_mibII_poll_timer();
 }
 
 /*
@@ -1651,6 +1678,11 @@ mibII_init(struct lmodule *mod, int argc __unused, char *argv[] __unused)
 static int
 mibII_fini(void)
 {
+	if (mibII_poll_timer != NULL ) {
+		timer_stop(mibII_poll_timer);
+		mibII_poll_timer = NULL;
+	}
+
 	if (route_fd != NULL)
 		fd_deselect(route_fd);
 	if (route != -1)
@@ -1690,7 +1722,7 @@ const struct snmp_module config = {
 	"This module implements the interface and ip groups.",
 	mibII_init,
 	mibII_fini,
-	mibII_idle,	/* idle */
+	NULL,		/* idle */
 	NULL,		/* dump */
 	NULL,		/* config */
 	mibII_start,