Btrfs: More throttle tuning

* Make walk_down_tree wake up throttled tasks more often
* Make walk_down_tree call cond_resched during long loops
* As the size of the ref cache grows, wait longer in throttle
* Get rid of the reada code in walk_down_tree, the leaves don't get
  read anymore, thanks to the ref cache.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 9d84daf1000..cf73342e821 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -210,7 +210,9 @@ static noinline int wait_for_commit(struct btrfs_root *root,
 static void throttle_on_drops(struct btrfs_root *root)
 {
 	struct btrfs_fs_info *info = root->fs_info;
+	int harder_count = 0;
 
+harder:
 	if (atomic_read(&info->throttles)) {
 		DEFINE_WAIT(wait);
 		int thr;
@@ -226,6 +228,19 @@ static void throttle_on_drops(struct btrfs_root *root)
 			schedule();
 			finish_wait(&info->transaction_throttle, &wait);
 		} while (thr == atomic_read(&info->throttle_gen));
+		harder_count++;
+
+		if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
+		    harder_count < 2)
+			goto harder;
+
+		if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
+		    harder_count < 10)
+			goto harder;
+
+		if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
+		    harder_count < 20)
+			goto harder;
 	}
 }