Index: sys/pool.h
===================================================================
RCS file: /cvs/src/sys/sys/pool.h,v
retrieving revision 1.70
diff -u -p -r1.70 pool.h
--- sys/pool.h	15 Jun 2017 02:52:30 -0000	1.70
+++ sys/pool.h	15 Jun 2017 11:28:31 -0000
@@ -185,11 +185,13 @@ struct pool {
 	unsigned long	pr_cache_magic[2];
 	struct mutex	pr_cache_mtx;
 	struct pool_cache_lists
-			pr_cache_lists;
-	u_int		pr_cache_nlist;	/* # of lists */
+			pr_cache_lists;	/* list of idle item lists */
+	u_int		pr_cache_nlist;	/* # of idle lists */
 	u_int		pr_cache_items;	/* target list length */
 	u_int		pr_cache_contention;
+	int		pr_cache_tick;	/* time idle list was empty */
 	int		pr_cache_nout;
+	uint64_t	pr_cache_ngc;	/* # of times the gc released a list */
 
 	u_int		pr_align;
 	u_int		pr_maxcolors;	/* Cache coloring */
Index: kern/subr_pool.c
===================================================================
RCS file: /cvs/src/sys/kern/subr_pool.c,v
retrieving revision 1.212
diff -u -p -r1.212 subr_pool.c
--- kern/subr_pool.c	15 Jun 2017 03:50:50 -0000	1.212
+++ kern/subr_pool.c	15 Jun 2017 11:28:31 -0000
@@ -1,4 +1,4 @@
-/*	$OpenBSD: subr_pool.c,v 1.212 2017/06/15 03:50:50 dlg Exp $	*/
+/*	$OpenBSD: subr_pool.c,v 1.211 2017/06/15 03:48:50 dlg Exp $	*/
 /*	$NetBSD: subr_pool.c,v 1.61 2001/09/26 07:14:56 chs Exp $	*/
 
 /*-
@@ -135,6 +135,7 @@ struct pool_cache {
 void	*pool_cache_get(struct pool *);
 void	 pool_cache_put(struct pool *, void *);
 void	 pool_cache_destroy(struct pool *);
+void	 pool_cache_gc(struct pool *);
 #endif
 void	 pool_cache_pool_info(struct pool *, struct kinfo_pool *);
 int	 pool_cache_info(struct pool *, void *, size_t *);
@@ -156,6 +157,7 @@ void	 pool_p_free(struct pool *, struct 
 
 void	 pool_update_curpage(struct pool *);
 void	*pool_do_get(struct pool *, int, int *);
+void	 pool_do_put(struct pool *, void *);
 int	 pool_chk_page(struct pool *, struct pool_page_header *, int);
 int	 pool_chk(struct pool *);
 void	 pool_get_done(void *, void *);
@@ -711,7 +713,6 @@ pool_do_get(struct pool *pp, int flags, 
 void
 pool_put(struct pool *pp, void *v)
 {
-	struct pool_item *pi = v;
 	struct pool_page_header *ph, *freeph = NULL;
 
 #ifdef DIAGNOSTIC
@@ -728,6 +729,37 @@ pool_put(struct pool *pp, void *v)
 
 	mtx_enter(&pp->pr_mtx);
 
+	pool_do_put(pp, v);
+
+	pp->pr_nout--;
+	pp->pr_nput++;
+
+	/* is it time to free a page? */
+	if (pp->pr_nidle > pp->pr_maxpages &&
+	    (ph = TAILQ_FIRST(&pp->pr_emptypages)) != NULL &&
+	    (ticks - ph->ph_tick) > (hz * pool_wait_free)) {
+		freeph = ph;
+		pool_p_remove(pp, freeph);
+	}
+
+	mtx_leave(&pp->pr_mtx);
+
+	if (freeph != NULL)
+		pool_p_free(pp, freeph);
+
+	if (!TAILQ_EMPTY(&pp->pr_requests)) {
+		mtx_enter(&pp->pr_requests_mtx);
+		pool_runqueue(pp, PR_NOWAIT);
+		mtx_leave(&pp->pr_requests_mtx);
+	}
+}
+
+void
+pool_do_put(struct pool *pp, void *v)
+{
+	struct pool_item *pi = v;
+	struct pool_page_header *ph;
+
 	splassert(pp->pr_ipl);
 
 	ph = pr_find_pagehead(pp, v);
@@ -771,27 +803,6 @@ pool_put(struct pool *pp, void *v)
 		TAILQ_INSERT_TAIL(&pp->pr_emptypages, ph, ph_entry);
 		pool_update_curpage(pp);
 	}
-
-	pp->pr_nout--;
-	pp->pr_nput++;
-
-	/* is it time to free a page? */
-	if (pp->pr_nidle > pp->pr_maxpages &&
-	    (ph = TAILQ_FIRST(&pp->pr_emptypages)) != NULL &&
-	    (ticks - ph->ph_tick) > (hz * pool_wait_free)) {
-		freeph = ph;
-		pool_p_remove(pp, freeph);
-	}
-	mtx_leave(&pp->pr_mtx);
-
-	if (freeph != NULL)
-		pool_p_free(pp, freeph);
-
-	if (!TAILQ_EMPTY(&pp->pr_requests)) {
-		mtx_enter(&pp->pr_requests_mtx);
-		pool_runqueue(pp, PR_NOWAIT);
-		mtx_leave(&pp->pr_requests_mtx);
-	}
 }
 
 /*
@@ -1466,6 +1477,11 @@ pool_gc_pages(void *null)
 	rw_enter_read(&pool_lock);
 	s = splvm(); /* XXX go to splvm until all pools _setipl properly */
 	SIMPLEQ_FOREACH(pp, &pool_head, pr_poollist) {
+#ifdef MULTIPROCESSOR
+		if (pp->pr_cache != NULL)
+			pool_cache_gc(pp);
+#endif
+
 		if (pp->pr_nidle <= pp->pr_minpages || /* guess */
 		    !mtx_enter_try(&pp->pr_mtx)) /* try */
 			continue;
@@ -1632,8 +1648,10 @@ pool_cache_init(struct pool *pp)
 	arc4random_buf(pp->pr_cache_magic, sizeof(pp->pr_cache_magic));
 	TAILQ_INIT(&pp->pr_cache_lists);
 	pp->pr_cache_nlist = 0;
+	pp->pr_cache_tick = ticks;
 	pp->pr_cache_items = 8;
 	pp->pr_cache_contention = 0;
+	pp->pr_cache_ngc = 0;
 
 	CPUMEM_FOREACH(pc, &i, cm) {
 		pc->pc_actv = NULL;
@@ -1649,6 +1667,8 @@ pool_cache_init(struct pool *pp)
 		pc->pc_nout = 0;
 	}
 
+	membar_producer();
+
 	pp->pr_cache = cm;
 }
 
@@ -1730,6 +1750,9 @@ pool_cache_list_free(struct pool *pp, st
     struct pool_cache_item *ci)
 {
 	pool_list_enter(pp);
+	if (TAILQ_EMPTY(&pp->pr_cache_lists))
+		pp->pr_cache_tick = ticks;
+
 	TAILQ_INSERT_TAIL(&pp->pr_cache_lists, ci, ci_nextl);
 	pp->pr_cache_nlist++;
 
@@ -1864,11 +1887,13 @@ pool_cache_list_put(struct pool *pp, str
 
 	rpl = TAILQ_NEXT(pl, ci_nextl);
 
+	mtx_enter(&pp->pr_mtx);
 	do {
 		next = pl->ci_next;
-		pool_put(pp, pl);
+		pool_do_put(pp, pl);
 		pl = next;
 	} while (pl != NULL);
+	mtx_leave(&pp->pr_mtx);
 
 	return (rpl);
 }
@@ -1881,8 +1906,10 @@ pool_cache_destroy(struct pool *pp)
 	struct cpumem_iter i;
 	struct cpumem *cm;
 
+	rw_enter_write(&pool_lock); /* serialise with the gc */
 	cm = pp->pr_cache;
 	pp->pr_cache = NULL; /* make pool_put avoid the cache */
+	rw_exit_write(&pool_lock);
 
 	CPUMEM_FOREACH(pc, &i, cm) {
 		pool_cache_list_put(pp, pc->pc_actv);
@@ -1897,6 +1924,29 @@ pool_cache_destroy(struct pool *pp)
 }
 
 void
+pool_cache_gc(struct pool *pp)
+{
+	if ((ticks - pp->pr_cache_tick) > (hz * pool_wait_gc) &&
+	    !TAILQ_EMPTY(&pp->pr_cache_lists) &&
+	    mtx_enter_try(&pp->pr_cache_mtx)) {
+		struct pool_cache_item *pl = NULL;
+
+		pl = TAILQ_FIRST(&pp->pr_cache_lists);
+		if (pl != NULL) {
+			TAILQ_REMOVE(&pp->pr_cache_lists, pl, ci_nextl);
+			pp->pr_cache_tick = ticks;
+			pp->pr_cache_nlist--;
+
+			pp->pr_cache_ngc++;
+		}
+
+		mtx_leave(&pp->pr_cache_mtx);
+
+		pool_cache_list_put(pp, pl);
+	}
+}
+
+void
 pool_cache_pool_info(struct pool *pp, struct kinfo_pool *pi)
 {
 	struct pool_cache *pc;
@@ -1943,7 +1993,7 @@ pool_cache_info(struct pool *pp, void *o
 	memset(&kpc, 0, sizeof(kpc)); /* don't leak padding */
 
 	mtx_enter(&pp->pr_cache_mtx);
-	kpc.pr_ngc = 0; /* notyet */
+	kpc.pr_ngc = pp->pr_cache_ngc;
 	kpc.pr_len = pp->pr_cache_items;
 	kpc.pr_nlist = pp->pr_cache_nlist;
 	kpc.pr_contention = pp->pr_cache_contention;