>From Takashi

lock profiling shows 

- mpage_writepages
- sync_supers

Are causing latency problems.  This adds some conditional schedules to
help fix things

Index: linux-2.6.8.1/fs/fs-writeback.c
===================================================================
--- linux-2.6.8.1.orig/fs/fs-writeback.c	2004-08-15 14:08:15.000000000 +1000
+++ linux-2.6.8.1/fs/fs-writeback.c	2004-08-15 14:58:54.654062056 +1000
@@ -361,6 +361,7 @@ sync_sb_inodes(struct super_block *sb, s
 		}
 		spin_unlock(&inode_lock);
 		iput(inode);
+		cond_resched();
 		spin_lock(&inode_lock);
 		if (wbc->nr_to_write <= 0)
 			break;
@@ -420,6 +421,7 @@ restart:
 	}
 	spin_unlock(&sb_lock);
 	spin_unlock(&inode_lock);
+	cond_resched();
 }
 
 /*
Index: linux-2.6.8.1/fs/super.c
===================================================================
--- linux-2.6.8.1.orig/fs/super.c	2004-08-15 14:53:06.386262098 +1000
+++ linux-2.6.8.1/fs/super.c	2004-08-15 14:58:54.655061900 +1000
@@ -320,6 +320,7 @@ void sync_supers(void)
 {
 	struct super_block * sb;
 restart:
+	cond_resched();
 	spin_lock(&sb_lock);
 	sb = sb_entry(super_blocks.next);
 	while (sb != sb_entry(&super_blocks))