Debug patch

Add some debug printk's to watch how the cpuset specific throttling code is
doing.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.20-rc5/fs/fs-writeback.c
===================================================================
--- linux-2.6.20-rc5.orig/fs/fs-writeback.c	2007-01-22 14:04:23.000000000 -0600
+++ linux-2.6.20-rc5/fs/fs-writeback.c	2007-01-22 15:10:57.541888415 -0600
@@ -354,7 +354,11 @@ sync_sb_inodes(struct super_block *sb, s
 			/* No pages on the nodes under writeback */
 			list_move(&inode->i_list, &sb->s_dirty);
 			continue;
-		}
+		} else
+		if (wbc->nodes)
+			printk(KERN_INFO "sync_sb_inodes mapping=%p dirty_map=%lx allowed=%lx\n",
+				mapping, mapping->dirty_nodes ? mapping->dirty_nodes->bits[0]: -1,
+				wbc->nodes->bits[0]);
 
 		/* Was this inode dirtied after sync_sb_inodes was called? */
 		if (time_after(inode->dirtied_when, start))
@@ -385,6 +389,9 @@ sync_sb_inodes(struct super_block *sb, s
 			 * buffers.  Skip this inode for now.
 			 */
 			list_move(&inode->i_list, &sb->s_dirty);
+			if (wbc->nodes)
+			printk(KERN_INFO "sync_sb_inodes: No writeout progress on mapping=%p map=%lx\n",
+				mapping, mapping->dirty_nodes ? mapping->dirty_nodes->bits[0]: -1);
 		}
 		spin_unlock(&inode_lock);
 		iput(inode);
Index: linux-2.6.20-rc5/mm/page-writeback.c
===================================================================
--- linux-2.6.20-rc5.orig/mm/page-writeback.c	2007-01-22 15:10:52.000000000 -0600
+++ linux-2.6.20-rc5/mm/page-writeback.c	2007-01-22 15:10:57.579978052 -0600
@@ -271,6 +271,9 @@ static void balance_dirty_pages(struct a
 			if (nr_reclaimable + dl.nr_writeback <= dl.thresh_dirty)
 						break;
 			pages_written += write_chunk - wbc.nr_to_write;
+			if (pages_written)
+				printk(KERN_INFO "Sync writeback nodes=%lx wrote %ld pages triggered by mapping %p\n",
+				cpuset_current_mems_allowed.bits[0], pages_written, mapping);
 			if (pages_written >= write_chunk)
 				break;		/* We've done our duty */
 		}
@@ -293,9 +296,12 @@ static void balance_dirty_pages(struct a
 	 * background_thresh, to keep the amount of dirty memory low.
 	 */
 	if ((laptop_mode && pages_written) ||
-	     (!laptop_mode && (nr_reclaimable > dl.thresh_background)))
+	     (!laptop_mode && (nr_reclaimable > dl.thresh_background))) {
+		printk(KERN_INFO "Background writeback nodes=%lx triggered by mapping %p\n",
+				cpuset_current_mems_allowed.bits[0], mapping);
 		pdflush_operation(background_writeout, 0,
 			&cpuset_current_mems_allowed);
+	}
 }
 
 void set_page_dirty_balance(struct page *page)
@@ -398,6 +404,9 @@ static void background_writeout(unsigned
 		wbc.nr_to_write = MAX_WRITEBACK_PAGES;
 		wbc.pages_skipped = 0;
 		writeback_inodes(&wbc);
+		if (wbc.nodes)
+			printk(KERN_INFO "background_writeout: wrote %d pages.\n", MAX_WRITEBACK_PAGES -
+			wbc.nr_to_write);
 		min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
 		if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
 			/* Wrote less than expected */
@@ -415,10 +424,15 @@ static void background_writeout(unsigned
  */
 int wakeup_pdflush(long nr_pages, nodemask_t *nodes)
 {
+	int rc;
+
 	if (nr_pages == 0)
 		nr_pages = global_page_state(NR_FILE_DIRTY) +
 				global_page_state(NR_UNSTABLE_NFS);
-	return pdflush_operation(background_writeout, nr_pages, nodes);
+	rc = pdflush_operation(background_writeout, nr_pages, nodes);
+	printk(KERN_INFO "wakeup_pdflush(%ld,%lx) == %d\n",nr_pages, nodes ? nodes->bits[0]: 0,
+		rc);
+	return rc;
 }
 
 static void wb_timer_fn(unsigned long unused);
Index: linux-2.6.20-rc5/kernel/cpuset.c
===================================================================
--- linux-2.6.20-rc5.orig/kernel/cpuset.c	2007-01-22 15:10:52.000000000 -0600
+++ linux-2.6.20-rc5/kernel/cpuset.c	2007-01-22 15:15:47.355900028 -0600
@@ -2619,15 +2619,22 @@ void cpuset_update_dirty_nodes(struct ad
 
 	if (!nodes) {
 		nodes = kmalloc(sizeof(nodemask_t), GFP_ATOMIC);
-		if (!nodes)
+		if (!nodes) {
+			printk(KERN_INFO "cpuset_update_dirty_nodes: Cannot allocate nodemask for mapping=%p node=%d\n",
+			mapping, page_to_nid(page));
 			return;
+		}
 
 		*nodes = NODE_MASK_NONE;
 		mapping->dirty_nodes = nodes;
 	}
 
-	if (!node_isset(node, *nodes))
+	if (!node_isset(node, *nodes)) {
+		if (!node_isset(page_to_nid(page), *nodes))
+			printk(KERN_INFO "cpuset_update__dirty_nodes: Dirty map update mapping=%p node=%d prior=%lx\n",
+			mapping, page_to_nid(page), nodes->bits[0]);
 		node_set(node, *nodes);
+	}
 }
 
 void cpuset_clear_dirty_nodes(struct address_space *mapping)