==== //SpectraBSD/stable/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c#16 (text) - //SpectraBSD/stable/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c#19 (text) ==== content
@@ -2484,6 +2484,8 @@
 		uint64_t to_free;
 
 		to_free = arc_c >> arc_shrink_shift;
+		DTRACE_PROBE4(arc__shrink, uint64_t, arc_c,
+		    uint64_t, arc_c_min, uint64_t, arc_p, uint64_t, to_free);
 		if (arc_c > arc_c_min + to_free)
 			atomic_add_64(&arc_c, -to_free);
 		else
@@ -2494,12 +2496,18 @@
 			arc_c = MAX(arc_size, arc_c_min);
 		if (arc_p > arc_c)
 			arc_p = (arc_c >> 1);
+
+		DTRACE_PROBE2(arc__shrunk, uint64_t, arc_c, uint64_t, arc_p);
+
 		ASSERT(arc_c >= arc_c_min);
 		ASSERT((int64_t)arc_p >= 0);
 	}
 
-	if (arc_size > arc_c)
+	if (arc_size > arc_c) {
+		DTRACE_PROBE2(arc__shrink_adjust, uint64_t, arc_size,
+		    uint64_t, arc_c);
 		arc_adjust();
+	}
 }
 
 static int needfree = 0;
@@ -2509,6 +2517,8 @@
 {
 
 #ifdef _KERNEL
+	DTRACE_PROBE2(arc__reclaim_needed,
+	    int, needfree, int, vm_paging_needed());
 
 	if (needfree)
 		return (1);
@@ -2545,6 +2555,7 @@
 	 */
 	if (availrmem < swapfs_minfree + swapfs_reserve + extra)
 		return (1);
+#endif /* sun */
 
 #if defined(__i386)
 	/*
@@ -2558,14 +2569,10 @@
 	 * heap is allocated.  (Or, in the calculation, if less than 1/4th is
 	 * free)
 	 */
-	if (btop(vmem_size(heap_arena, VMEM_FREE)) <
-	    (btop(vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC)) >> 2))
+	if (vmem_size(heap_arena, VMEM_FREE) <
+	    (vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC) >> 2))
 		return (1);
 #endif
-#else	/* !sun */
-	if (kmem_used() > (kmem_size() * 3) / 4)
-		return (1);
-#endif	/* sun */
 
 #else	/* !_KERNEL */
 	if (spa_get_random(100) == 0)
@@ -2627,11 +2634,11 @@
 	clock_t			growtime = 0;
 	arc_reclaim_strategy_t	last_reclaim = ARC_RECLAIM_CONS;
 	callb_cpr_t		cpr;
+	int			last_needfree = 0;
 
 	CALLB_CPR_INIT(&cpr, &arc_reclaim_thr_lock, callb_generic_cpr, FTAG);
 
-	mutex_enter(&arc_reclaim_thr_lock);
-	while (arc_thread_exit == 0) {
+	for (;;) {
 		if (arc_reclaim_needed()) {
 
 			if (arc_no_grow) {
@@ -2646,6 +2653,10 @@
 				membar_producer();
 			}
 
+			DTRACE_PROBE2(arc__reclaim_strategy,
+			    int, arc_no_grow,
+			    arc_reclaim_strategy_t, last_reclaim);
+
 			/* reset the growth delay for every reclaim */
 			growtime = ddi_get_lbolt() + (arc_grow_retry * hz);
 
@@ -2670,18 +2681,27 @@
 		if (arc_eviction_list != NULL)
 			arc_do_user_evicts();
 
+		mutex_enter(&arc_reclaim_thr_lock);
+		if (arc_thread_exit != 0)
+			break;
+
+		needfree -= last_needfree;
+		VERIFY3S(needfree, >=, 0);
+		if (needfree == 0) {
+			/*
+			 * Block until needed, or one second,
+			 * whichever is shorter.
+			 */
 #ifdef _KERNEL
-		if (needfree) {
-			needfree = 0;
 			wakeup(&needfree);
+#endif
+			CALLB_CPR_SAFE_BEGIN(&cpr);
+			(void) cv_timedwait(&arc_reclaim_thr_cv,
+			    &arc_reclaim_thr_lock, hz);
+			CALLB_CPR_SAFE_END(&cpr, &arc_reclaim_thr_lock);
 		}
-#endif
-
-		/* block until needed, or one second, whichever is shorter */
-		CALLB_CPR_SAFE_BEGIN(&cpr);
-		(void) cv_timedwait(&arc_reclaim_thr_cv,
-		    &arc_reclaim_thr_lock, hz);
-		CALLB_CPR_SAFE_END(&cpr, &arc_reclaim_thr_lock);
+		last_needfree = needfree;
+		mutex_exit(&arc_reclaim_thr_lock);
 	}
 
 	arc_thread_exit = 0;
@@ -4067,13 +4087,12 @@
 static eventhandler_tag arc_event_lowmem = NULL;
 
 static void
-arc_lowmem(void *arg __unused, int howto __unused)
+arc_lowmem(void *arg __unused, int tries)
 {
 
-	/* Serialize access via arc_lowmem_lock. */
-	mutex_enter(&arc_lowmem_lock);
+	DTRACE_PROBE1(arc__lowmem_signaled, int, needfree);
 	mutex_enter(&arc_reclaim_thr_lock);
-	needfree = 1;
+	needfree++;
 	cv_signal(&arc_reclaim_thr_cv);
 
 	/*
@@ -4081,12 +4100,13 @@
 	 * here from ARC itself and may hold ARC locks and thus risk a deadlock
 	 * with ARC reclaim thread.
 	 */
-	if (curproc == pageproc) {
+	if (tries > 1 && curproc == pageproc) {
 		while (needfree)
-			msleep(&needfree, &arc_reclaim_thr_lock, 0, "zfs:lowmem", 0);
+			msleep(&needfree, &arc_reclaim_thr_lock, 0,
+			    "zfs:lowmem", 0);
 	}
+
 	mutex_exit(&arc_reclaim_thr_lock);
-	mutex_exit(&arc_lowmem_lock);
 }
 #endif
 
==== //SpectraBSD/stable/sys/vm/vm_pageout.c#8 (text) ====

@@ -663,7 +663,7 @@
 		 * may acquire locks and/or sleep, so they can only be invoked
 		 * when "tries" is greater than zero.
 		 */
-		EVENTHANDLER_INVOKE(vm_lowmem, 0);
+		EVENTHANDLER_INVOKE(vm_lowmem, tries);
 
 		/*
 		 * We do this explicitly after the caches have been drained
@@ -925,7 +925,7 @@
 		/*
 		 * Decrease registered cache sizes.
 		 */
-		EVENTHANDLER_INVOKE(vm_lowmem, 0);
+		EVENTHANDLER_INVOKE(vm_lowmem, pass);
 		/*
 		 * We do this explicitly after the caches have been
 		 * drained above.