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

5 files changed, 77 insertions, 3 deletions

diff --git a/contrib/bsnmp/snmp_mibII/BEGEMOT-MIB2-MIB.txt b/contrib/bsnmp/snmp_mibII/BEGEMOT-MIB2-MIB.txt
index 32cf7a6..fa0dba3 100644
--- a/contrib/bsnmp/snmp_mibII/BEGEMOT-MIB2-MIB.txt
+++ b/contrib/bsnmp/snmp_mibII/BEGEMOT-MIB2-MIB.txt
@@ -39,7 +39,7 @@ IMPORTS
 	FROM BEGEMOT-IP-MIB;
 
 begemotMib2 MODULE-IDENTITY
-    LAST-UPDATED "200602130000Z"
+    LAST-UPDATED "200908030000Z"
     ORGANIZATION "German Aerospace Center"
     CONTACT-INFO
 	    "		Hartmut Brandt
@@ -54,6 +54,12 @@ begemotMib2 MODULE-IDENTITY
 	     E-mail:	harti@freebsd.org"
     DESCRIPTION
 	    "The MIB for private mib2 stuff."
+    REVISION	"200908030000Z"
+    DESCRIPTION
+		"Second edition adds begemotIfDataPoll object."
+    REVISION	"200602130000Z"
+    DESCRIPTION
+		"Initial revision."
     ::= { begemotIp 1 }
 
 begemotIfMaxspeed OBJECT-TYPE
@@ -87,4 +93,14 @@ begemotIfForcePoll OBJECT-TYPE
 	     bit rate in its MIB."
     ::= { begemotMib2 3 }
 
+begemotIfDataPoll OBJECT-TYPE
+    SYNTAX	TimeTicks
+    UNITS	"deciseconds"
+    MAX-ACCESS	read-write
+    STATUS	current
+    DESCRIPTION
+	    "The rate at which the mib2 module will poll interface data."
+    DEFVAL	{ 100 }
+    ::= { begemotMib2 4 }
+
 END
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,
diff --git a/contrib/bsnmp/snmp_mibII/mibII.h b/contrib/bsnmp/snmp_mibII/mibII.h
index a21e023..0ebde9a 100644
--- a/contrib/bsnmp/snmp_mibII/mibII.h
+++ b/contrib/bsnmp/snmp_mibII/mibII.h
@@ -211,6 +211,14 @@ extern u_int mibif_hc_update_interval;
 /* re-compute update interval */
 void mibif_reset_hc_timer(void);
 
+/* interfaces' data poll interval */
+extern u_int mibII_poll_ticks;
+
+/* restart the data poll timer */
+void mibif_restart_mibII_poll_timer(void);
+
+#define MIBII_POLL_TICKS	100
+
 /* get interfaces and interface addresses. */
 void mib_fetch_interfaces(void);
 
diff --git a/contrib/bsnmp/snmp_mibII/mibII_begemot.c b/contrib/bsnmp/snmp_mibII/mibII_begemot.c
index 5841b81..b502e95 100644
--- a/contrib/bsnmp/snmp_mibII/mibII_begemot.c
+++ b/contrib/bsnmp/snmp_mibII/mibII_begemot.c
@@ -59,6 +59,11 @@ op_begemot_mibII(struct snmp_context *ctx __unused, struct snmp_value *value,
 			ctx->scratch->int1 = mibif_force_hc_update_interval;
 			mibif_force_hc_update_interval = value->v.uint32;
 			return (SNMP_ERR_NOERROR);
+
+		  case LEAF_begemotIfDataPoll:
+			ctx->scratch->int1 = mibII_poll_ticks;
+			mibII_poll_ticks = value->v.uint32;
+			return (SNMP_ERR_NOERROR);
 		}
 		abort();
 
@@ -68,6 +73,10 @@ op_begemot_mibII(struct snmp_context *ctx __unused, struct snmp_value *value,
 		  case LEAF_begemotIfForcePoll:
 			mibif_force_hc_update_interval = ctx->scratch->int1;
 			return (SNMP_ERR_NOERROR);
+
+		  case LEAF_begemotIfDataPoll:
+			mibII_poll_ticks = ctx->scratch->int1;
+			return (SNMP_ERR_NOERROR);
 		}
 		abort();
 
@@ -78,6 +87,10 @@ op_begemot_mibII(struct snmp_context *ctx __unused, struct snmp_value *value,
 			mibif_force_hc_update_interval = ctx->scratch->int1;
 			mibif_reset_hc_timer();
 			return (SNMP_ERR_NOERROR);
+
+		  case LEAF_begemotIfDataPoll:
+			mibif_restart_mibII_poll_timer();
+			return (SNMP_ERR_NOERROR);
 		}
 		abort();
 	}
@@ -98,6 +111,10 @@ op_begemot_mibII(struct snmp_context *ctx __unused, struct snmp_value *value,
 	  case LEAF_begemotIfForcePoll:
 		value->v.uint32 = mibif_force_hc_update_interval;
 		return (SNMP_ERR_NOERROR);
+
+	  case LEAF_begemotIfDataPoll:
+		value->v.uint32 = mibII_poll_ticks;
+		return (SNMP_ERR_NOERROR);
 	}
 	abort();
 }
diff --git a/contrib/bsnmp/snmp_mibII/mibII_tree.def b/contrib/bsnmp/snmp_mibII/mibII_tree.def
index 90fbb03..d377538 100644
--- a/contrib/bsnmp/snmp_mibII/mibII_tree.def
+++ b/contrib/bsnmp/snmp_mibII/mibII_tree.def
@@ -240,6 +240,7 @@
 		(1 begemotIfMaxspeed COUNTER64 op_begemot_mibII GET)
 		(2 begemotIfPoll TIMETICKS op_begemot_mibII GET)
 		(3 begemotIfForcePoll TIMETICKS op_begemot_mibII GET SET)
+		(4 begemotIfDataPoll TIMETICKS op_begemot_mibII GET SET)
 	      )
 	    )
 	  )