Index: sys/vm/vm_pageout.c
===================================================================
--- sys/vm/vm_pageout.c
+++ sys/vm/vm_pageout.c
@@ -166,10 +166,11 @@
 	"Maximum active LRU update period");
 
 /* Access with get_pageout_threads_per_domain(). */
-static int pageout_threads_per_domain = 1;
-SYSCTL_INT(_vm, OID_AUTO, pageout_threads_per_domain, CTLFLAG_RDTUN,
-    &pageout_threads_per_domain, 0,
-    "Number of worker threads comprising each per-domain pagedaemon");
+static int pageout_threads_per_domain;
+static int pageout_cpus_per_thread = 16;
+SYSCTL_INT(_vm, OID_AUTO, pageout_cpus_per_thread, CTLFLAG_RDTUN,
+    &pageout_cpus_per_thread, 0,
+    "Number of CPUs per pagedaemon worker thread");
   
 SYSCTL_INT(_vm, OID_AUTO, lowmem_period, CTLFLAG_RWTUN, &lowmem_period, 0,
 	"Low memory callback period");
@@ -2203,33 +2204,29 @@
 get_pageout_threads_per_domain(void)
 {
 	static bool resolved = false;
-	int half_cpus_per_dom;
+	int cpus_per_dom;
 
 	/*
 	 * This is serialized externally by the sorted autoconfig portion of
 	 * boot.
 	 */
-	if (__predict_true(resolved))
+	if (resolved)
 		return (pageout_threads_per_domain);
 
+	cpus_per_dom = howmany(mp_ncpus, vm_ndomains);
+
 	/*
 	 * Semi-arbitrarily constrain pagedaemon threads to less than half the
-	 * total number of threads in the system as an insane upper limit.
+	 * total number of CPUs in the system as an upper limit.
 	 */
-	half_cpus_per_dom = howmany(mp_ncpus / vm_ndomains, 2);
+	if (pageout_cpus_per_thread < 2)
+		pageout_cpus_per_thread = 2;
+	else if (pageout_cpus_per_thread > cpus_per_dom)
+		pageout_cpus_per_thread = cpus_per_dom;
+
+	pageout_threads_per_domain = howmany(cpus_per_dom,
+	    pageout_cpus_per_thread);
 
-	if (pageout_threads_per_domain < 1) {
-		printf("Invalid tuneable vm.pageout_threads_per_domain value: "
-		    "%d out of valid range: [1-%d]; clamping to 1\n",
-		    pageout_threads_per_domain, half_cpus_per_dom);
-		pageout_threads_per_domain = 1;
-	} else if (pageout_threads_per_domain > half_cpus_per_dom) {
-		printf("Invalid tuneable vm.pageout_threads_per_domain value: "
-		    "%d out of valid range: [1-%d]; clamping to %d\n",
-		    pageout_threads_per_domain, half_cpus_per_dom,
-		    half_cpus_per_dom);
-		pageout_threads_per_domain = half_cpus_per_dom;
-	}
 	resolved = true;
 	return (pageout_threads_per_domain);
 }