svn commit: r338698 - head/sys/netpfil/pf

[John-Mark Gurney]

Author: jmg
Date: Sun Sep 16 00:44:23 2018
New Revision: 338698
URL: https://svnweb.freebsd.org/changeset/base/338698

Log:
  Significantly improve pf purge cpu usage by only taking locks
  when there is work to do.  This reduces CPU consumption to one
  third on systems.  This will help keep the thread CPU usage under
  control now that the default hash size has increased.
  
  Reviewed by:	kp
  Approved by:	re (kib)
  Differential Revision:	https://reviews.freebsd.org/D17097

Modified:
  head/sys/netpfil/pf/pf.c

Modified: head/sys/netpfil/pf/pf.c
==============================================================================
--- head/sys/netpfil/pf/pf.c	Sat Sep 15 21:22:50 2018	(r338697)
+++ head/sys/netpfil/pf/pf.c	Sun Sep 16 00:44:23 2018	(r338698)
@@ -1719,24 +1719,28 @@ pf_purge_expired_states(u_int i, int maxcheck)
 	while (maxcheck > 0) {
 
 		ih = &V_pf_idhash[i];
+
+		/* only take the lock if we expect to do work */
+		if (!LIST_EMPTY(&ih->states)) {
 relock:
-		PF_HASHROW_LOCK(ih);
-		LIST_FOREACH(s, &ih->states, entry) {
-			if (pf_state_expires(s) <= time_uptime) {
-				V_pf_status.states -=
-				    pf_unlink_state(s, PF_ENTER_LOCKED);
-				goto relock;
+			PF_HASHROW_LOCK(ih);
+			LIST_FOREACH(s, &ih->states, entry) {
+				if (pf_state_expires(s) <= time_uptime) {
+					V_pf_status.states -=
+					    pf_unlink_state(s, PF_ENTER_LOCKED);
+					goto relock;
+				}
+				s->rule.ptr->rule_flag |= PFRULE_REFS;
+				if (s->nat_rule.ptr != NULL)
+					s->nat_rule.ptr->rule_flag |= PFRULE_REFS;
+				if (s->anchor.ptr != NULL)
+					s->anchor.ptr->rule_flag |= PFRULE_REFS;
+				s->kif->pfik_flags |= PFI_IFLAG_REFS;
+				if (s->rt_kif)
+					s->rt_kif->pfik_flags |= PFI_IFLAG_REFS;
 			}
-			s->rule.ptr->rule_flag |= PFRULE_REFS;
-			if (s->nat_rule.ptr != NULL)
-				s->nat_rule.ptr->rule_flag |= PFRULE_REFS;
-			if (s->anchor.ptr != NULL)
-				s->anchor.ptr->rule_flag |= PFRULE_REFS;
-			s->kif->pfik_flags |= PFI_IFLAG_REFS;
-			if (s->rt_kif)
-				s->rt_kif->pfik_flags |= PFI_IFLAG_REFS;
+			PF_HASHROW_UNLOCK(ih);
 		}
-		PF_HASHROW_UNLOCK(ih);
 
 		/* Return when we hit end of hash. */
 		if (++i > pf_hashmask) {