From 29b3ca0a0800894b563b16463dc62bf00433506d Mon Sep 17 00:00:00 2001
From: Justus Winter <4winter@informatik.uni-hamburg.de>
Date: Sat, 21 Feb 2015 00:05:31 +0100
Subject: [PATCH gnumach 2/3] vm: keep track of clean pages

* vm/vm_page.h (struct vm_page): New field `cleanq'.
(vm_page_queue_clean): New declaration.
(vm_page_clean_count): Likewise.
(vm_page_queue_clean_lock): Likewise.
(vm_page_mark_dirty): New function to set and clear the dirty flag.
* vm/vm_resident.c (vm_page_queue_clean): New variable.
(vm_page_queue_clean_lock): Likewise.
(vm_page_clean_count): Likewise.
(vm_page_bootstrap): Initialize field `cleanq', the queue and the lock.
(vm_page_free): Get freed pages off the clean queue.
* linux/dev/glue/block.c: Use `vm_page_mark_dirty'.
* vm/memory_object.c: Likewise.
* vm/vm_debug.c: Likewise.
* vm/vm_fault.c: Likewise.
* vm/vm_map.c: Likewise.
* vm/vm_object.c: Likewise.
* vm/vm_pageout.c: Likewise.
* xen/block.c: Likewise.
---
 linux/dev/glue/block.c |  2 +-
 vm/memory_object.c     |  4 ++--
 vm/vm_debug.c          |  2 +-
 vm/vm_fault.c          |  6 +++---
 vm/vm_map.c            |  2 +-
 vm/vm_object.c         |  4 ++--
 vm/vm_page.h           | 33 +++++++++++++++++++++++++++++++--
 vm/vm_pageout.c        |  9 +++++----
 vm/vm_resident.c       | 10 ++++++++++
 xen/block.c            |  2 +-
 10 files changed, 57 insertions(+), 17 deletions(-)

diff --git a/linux/dev/glue/block.c b/linux/dev/glue/block.c
index da4ef38..3bd2c5b 100644
--- a/linux/dev/glue/block.c
+++ b/linux/dev/glue/block.c
@@ -1537,7 +1537,7 @@ device_read (void *d, ipc_port_t reply_port,
 	  if (dirty)
 	    {
 	      PAGE_WAKEUP_DONE (m);
-	      m->dirty = TRUE;
+	      vm_page_mark_dirty (m, TRUE);
 	      vm_page_insert (m, object, o);
 	    }
 	  else
diff --git a/vm/memory_object.c b/vm/memory_object.c
index 0a07429..55d8084 100644
--- a/vm/memory_object.c
+++ b/vm/memory_object.c
@@ -210,7 +210,7 @@ retry_lookup:
 		 */
 
 		data_m->busy = FALSE;
-		data_m->dirty = FALSE;
+		vm_page_mark_dirty (data_m, FALSE);
 		pmap_clear_modify(data_m->phys_addr);
 
 		data_m->page_lock = lock_value;
@@ -557,7 +557,7 @@ memory_object_lock_result_t memory_object_lock_page(
 		 */
 
 		if (!m->dirty)
-			m->dirty = pmap_is_modified(m->phys_addr);
+			vm_page_mark_dirty (m, pmap_is_modified(m->phys_addr));
 
 		if (m->dirty || (m->precious &&
 				 should_return == MEMORY_OBJECT_RETURN_ALL)) {
diff --git a/vm/vm_debug.c b/vm/vm_debug.c
index 227090e..822ca86 100644
--- a/vm/vm_debug.c
+++ b/vm/vm_debug.c
@@ -352,7 +352,7 @@ mach_vm_object_pages(
 		if (((state & (VPI_STATE_NODATA|VPI_STATE_DIRTY)) == 0) &&
 		    pmap_is_modified(p->phys_addr)) {
 			state |= VPI_STATE_DIRTY;
-			p->dirty = TRUE;
+			vm_page_mark_dirty (p, TRUE);
 		}
 
 		vm_page_lock_queues();
diff --git a/vm/vm_fault.c b/vm/vm_fault.c
index 101ebce..935b7b7 100644
--- a/vm/vm_fault.c
+++ b/vm/vm_fault.c
@@ -997,7 +997,7 @@ vm_fault_return_t vm_fault_page(
 
 			vm_page_lock_queues();
 			pmap_page_protect(m->phys_addr, VM_PROT_NONE);
-			copy_m->dirty = TRUE;
+			vm_page_mark_dirty (copy_m, TRUE);
 			vm_page_unlock_queues();
 
 			/*
@@ -1096,7 +1096,7 @@ vm_fault_return_t vm_fault_page(
 	 */
 
 	if (vm_fault_dirty_handling && (*protection & VM_PROT_WRITE))
-		m->dirty = TRUE;
+		vm_page_mark_dirty (m, TRUE);
 
 	return(VM_FAULT_SUCCESS);
 
@@ -1976,7 +1976,7 @@ kern_return_t	vm_fault_copy(
 			vm_page_zero_fill(dst_page);
 		else
 			vm_page_copy(src_page, dst_page);
-		dst_page->dirty = TRUE;
+		vm_page_mark_dirty (dst_page, TRUE);
 
 		/*
 		 *	Unlock everything, and return
diff --git a/vm/vm_map.c b/vm/vm_map.c
index 9098dfd..5e3fc2d 100644
--- a/vm/vm_map.c
+++ b/vm/vm_map.c
@@ -2960,7 +2960,7 @@ insert_pages:
 		assert(!m->wanted);
 
 		m->busy = FALSE;
-		m->dirty = TRUE;
+		vm_page_mark_dirty (m, TRUE);
 		vm_page_replace(m, object, old_last_offset + offset);
 		if (must_wire) {
 			vm_page_wire(m);
diff --git a/vm/vm_object.c b/vm/vm_object.c
index f97a3fd..4d882c1 100644
--- a/vm/vm_object.c
+++ b/vm/vm_object.c
@@ -588,7 +588,7 @@ void vm_object_terminate(
 		}
 
 		if (!p->dirty)
-			p->dirty = pmap_is_modified(p->phys_addr);
+			vm_page_mark_dirty (p, pmap_is_modified(p->phys_addr));
 
 		if (p->dirty || p->precious) {
 			p->busy = TRUE;
@@ -1096,7 +1096,7 @@ kern_return_t vm_object_copy_slowly(
 					 */
 
 					new_page->busy = FALSE;
-					new_page->dirty = TRUE;
+					vm_page_mark_dirty (new_page, TRUE);
 					vm_object_lock(result_page->object);
 					PAGE_WAKEUP_DONE(result_page);
 
diff --git a/vm/vm_page.h b/vm/vm_page.h
index e6a8c49..41c5711 100644
--- a/vm/vm_page.h
+++ b/vm/vm_page.h
@@ -70,8 +70,10 @@
  *	and sundry status bits.
  *
  *	Fields in this structure are locked either by the lock on the
- *	object that the page belongs to (O) or by the lock on the page
- *	queues (P).  [Some fields require that both locks be held to
+ *	object that the page belongs to (O), by the lock on the page
+ *	queues (P), or by vm_page_queue_clean_lock (C).
+ *
+ *	[Some fields require that both locks, O and P, be held to
  *	change that field; holding either lock is sufficient to read.]
  */
 
@@ -79,6 +81,7 @@ struct vm_page {
 	queue_chain_t	pageq;		/* queue info for FIFO
 					 * queue or free list (P) */
 	queue_chain_t	listq;		/* all pages in same object (O) */
+	queue_chain_t	cleanq;		/* all clean pages (C) */
 	struct vm_page	*next;		/* VP bucket link (O) */
 
 	vm_object_t	object;		/* which object am I in (O,P) */
@@ -147,8 +150,12 @@ extern
 queue_head_t	vm_page_queue_active;	/* active memory queue */
 extern
 queue_head_t	vm_page_queue_inactive;	/* inactive memory queue */
+extern
+queue_head_t	vm_page_queue_clean;	/* clean memory queue */
 
 extern
+int	vm_page_clean_count;	/* How many pages are clean? */
+extern
 int	vm_page_free_count;	/* How many pages are free? */
 extern
 int	vm_page_fictitious_count;/* How many fictitious pages are free? */
@@ -184,6 +191,8 @@ decl_simple_lock_data(extern,vm_page_queue_lock)/* lock on active and inactive
 						   page queues */
 decl_simple_lock_data(extern,vm_page_queue_free_lock)
 						/* lock on free page queue */
+decl_simple_lock_data(extern,vm_page_queue_clean_lock)
+						/* lock on clean page queue */
 
 extern unsigned int	vm_page_free_wanted;
 				/* how many threads are waiting for memory */
@@ -312,4 +321,24 @@ extern unsigned int	vm_page_info(
 	}							\
 	MACRO_END
 
+static inline void
+vm_page_mark_dirty (vm_page_t m, boolean_t dirty)
+{
+	if (m->dirty == dirty && (dirty || m->cleanq.next))
+		return;	/* No action necessary.  */
+
+	simple_lock (&vm_page_queue_clean_lock);
+	if (dirty && m->cleanq.next) {
+		queue_remove (&vm_page_queue_clean, m, vm_page_t, cleanq);
+		vm_page_clean_count -= 1;
+		m->cleanq.next = NULL;
+	}
+	if (! dirty) {
+		queue_enter (&vm_page_queue_clean, m, vm_page_t, cleanq);
+		vm_page_clean_count += 1;
+	}
+	simple_unlock (&vm_page_queue_clean_lock);
+	m->dirty = dirty;
+}
+
 #endif	/* _VM_VM_PAGE_H_ */
diff --git a/vm/vm_pageout.c b/vm/vm_pageout.c
index d0d124d..a8db604 100644
--- a/vm/vm_pageout.c
+++ b/vm/vm_pageout.c
@@ -292,7 +292,7 @@ vm_pageout_setup(
 		vm_page_insert(m, new_object, new_offset);
 		vm_page_unlock_queues();
 
-		m->dirty = TRUE;
+		vm_page_mark_dirty (m, TRUE);
 		m->precious = FALSE;
 		m->page_lock = VM_PROT_NONE;
 		m->unlock_request = VM_PROT_NONE;
@@ -304,7 +304,8 @@ vm_pageout_setup(
 		 */
 		vm_page_copy(m, new_m);
 
-		m->dirty = FALSE;
+		vm_object_lock(old_object);
+		vm_page_mark_dirty (m, FALSE);
 		pmap_clear_modify(m->phys_addr);
 
 		/*
@@ -332,7 +333,7 @@ vm_pageout_setup(
 		 *	Use the new page below.
 		 */
 		m = new_m;
-		m->dirty = TRUE;
+		vm_page_mark_dirty (m, TRUE);
 		assert(!m->precious);
 		PAGE_WAKEUP_DONE(m);
 	}
@@ -777,7 +778,7 @@ void vm_pageout_scan(void)
 		m->busy = TRUE;
 		pmap_page_protect(m->phys_addr, VM_PROT_NONE);
 		if (!m->dirty)
-			m->dirty = pmap_is_modified(m->phys_addr);
+			vm_page_mark_dirty (m, pmap_is_modified(m->phys_addr));
 
 		if (m->external) {
 			/* Figure out if we still care about this
diff --git a/vm/vm_resident.c b/vm/vm_resident.c
index b65b756..46980fc 100644
--- a/vm/vm_resident.c
+++ b/vm/vm_resident.c
@@ -148,9 +148,12 @@ vm_offset_t vm_page_fictitious_addr = (vm_offset_t) -1;
 queue_head_t	vm_page_queue_active;
 queue_head_t	vm_page_queue_inactive;
 decl_simple_lock_data(,vm_page_queue_lock)
+queue_head_t	vm_page_queue_clean;
+decl_simple_lock_data(,vm_page_queue_clean_lock)
 int	vm_page_active_count;
 int	vm_page_inactive_count;
 int	vm_page_wire_count;
+int	vm_page_clean_count;
 
 /*
  *	Several page replacement parameters are also
@@ -200,6 +203,7 @@ void vm_page_bootstrap(
 	 */
 
 	m = &vm_page_template;
+	m->cleanq.next = NULL;
 	m->object = VM_OBJECT_NULL;	/* reset later */
 	m->offset = 0;			/* reset later */
 	m->wire_count = 0;
@@ -231,12 +235,14 @@ void vm_page_bootstrap(
 	 */
 
 	simple_lock_init(&vm_page_queue_free_lock);
+	simple_lock_init(&vm_page_queue_clean_lock);
 	simple_lock_init(&vm_page_queue_lock);
 
 	vm_page_queue_free = VM_PAGE_NULL;
 	vm_page_queue_fictitious = VM_PAGE_NULL;
 	queue_init(&vm_page_queue_active);
 	queue_init(&vm_page_queue_inactive);
+	queue_init(&vm_page_queue_clean);
 
 	vm_page_free_wanted = 0;
 
@@ -1304,6 +1310,10 @@ void vm_page_free(
 	if (mem->absent)
 		vm_object_absent_release(mem->object);
 
+
+	/* Get it off the clean list.  */
+	vm_page_mark_dirty (mem, TRUE);
+
 	/*
 	 *	XXX The calls to vm_page_init here are
 	 *	really overkill.
diff --git a/xen/block.c b/xen/block.c
index d98b31e..175955a 100644
--- a/xen/block.c
+++ b/xen/block.c
@@ -539,7 +539,7 @@ device_read (void *d, ipc_port_t reply_port,
 	  assert (m->busy);
 	  vm_page_lock_queues ();
 	  PAGE_WAKEUP_DONE (m);
-	  m->dirty = TRUE;
+	  vm_page_mark_dirty (m, TRUE);
 	  vm_page_insert (m, object, o);
 	  vm_page_unlock_queues ();
 	  o += PAGE_SIZE;
-- 
2.1.4