[PATCH 1/5] xfs: track deferred ops statistics

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Track some basic statistics on how hard we're pushing the defer ops.

Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
 include/xfs_trans.h |    4 ++++
 libxfs/xfs_defer.c  |   18 +++++++++++++++++-
 2 files changed, 21 insertions(+), 1 deletion(-)


diff --git a/include/xfs_trans.h b/include/xfs_trans.h
index 248064019a0ab5..64d73c36851b75 100644
--- a/include/xfs_trans.h
+++ b/include/xfs_trans.h
@@ -82,6 +82,10 @@ typedef struct xfs_trans {
 	long			t_frextents_delta;/* superblock freextents chg*/
 	struct list_head	t_items;	/* log item descriptors */
 	struct list_head	t_dfops;	/* deferred operations */
+
+	unsigned int	t_dfops_nr;
+	unsigned int	t_dfops_nr_max;
+	unsigned int	t_dfops_finished;
 } xfs_trans_t;
 
 void	xfs_trans_init(struct xfs_mount *);
diff --git a/libxfs/xfs_defer.c b/libxfs/xfs_defer.c
index 8f6708c0f3bfcd..7e6167949f6509 100644
--- a/libxfs/xfs_defer.c
+++ b/libxfs/xfs_defer.c
@@ -611,6 +611,8 @@ xfs_defer_finish_one(
 	/* Done with the dfp, free it. */
 	list_del(&dfp->dfp_list);
 	kmem_cache_free(xfs_defer_pending_cache, dfp);
+	tp->t_dfops_nr--;
+	tp->t_dfops_finished++;
 out:
 	if (ops->finish_cleanup)
 		ops->finish_cleanup(tp, state, error);
@@ -673,6 +675,9 @@ xfs_defer_finish_noroll(
 
 		list_splice_init(&(*tp)->t_dfops, &dop_pending);
 
+		(*tp)->t_dfops_nr_max = max((*tp)->t_dfops_nr,
+					    (*tp)->t_dfops_nr_max);
+
 		if (has_intents < 0) {
 			error = has_intents;
 			goto out_shutdown;
@@ -714,6 +719,7 @@ xfs_defer_finish_noroll(
 	xfs_force_shutdown((*tp)->t_mountp, SHUTDOWN_CORRUPT_INCORE);
 	trace_xfs_defer_finish_error(*tp, error);
 	xfs_defer_cancel_list((*tp)->t_mountp, &dop_pending);
+	(*tp)->t_dfops_nr = 0;
 	xfs_defer_cancel(*tp);
 	return error;
 }
@@ -761,6 +767,7 @@ xfs_defer_cancel(
 	trace_xfs_defer_cancel(tp, _RET_IP_);
 	xfs_defer_trans_abort(tp, &tp->t_dfops);
 	xfs_defer_cancel_list(mp, &tp->t_dfops);
+	tp->t_dfops_nr = 0;
 }
 
 /*
@@ -846,8 +853,10 @@ xfs_defer_add(
 	}
 
 	dfp = xfs_defer_find_last(tp, ops);
-	if (!dfp || !xfs_defer_can_append(dfp, ops))
+	if (!dfp || !xfs_defer_can_append(dfp, ops)) {
 		dfp = xfs_defer_alloc(&tp->t_dfops, ops);
+		tp->t_dfops_nr++;
+	}
 
 	xfs_defer_add_item(dfp, li);
 	trace_xfs_defer_add_item(tp->t_mountp, dfp, li);
@@ -872,6 +881,7 @@ xfs_defer_add_barrier(
 		return;
 
 	xfs_defer_alloc(&tp->t_dfops, &xfs_barrier_defer_type);
+	tp->t_dfops_nr++;
 
 	trace_xfs_defer_add_item(tp->t_mountp, dfp, NULL);
 }
@@ -932,6 +942,12 @@ xfs_defer_move(
 	struct xfs_trans	*stp)
 {
 	list_splice_init(&stp->t_dfops, &dtp->t_dfops);
+	dtp->t_dfops_nr += stp->t_dfops_nr;
+	dtp->t_dfops_nr_max = stp->t_dfops_nr_max;
+	dtp->t_dfops_finished = stp->t_dfops_finished;
+	stp->t_dfops_nr = 0;
+	stp->t_dfops_nr_max = 0;
+	stp->t_dfops_finished = 0;
 
 	/*
 	 * Low free space mode was historically controlled by a dfops field.