[PATCH 7/8] rcu: add # of deferred _special() statistics

[Lai Jiangshan]

Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
 kernel/rcutree.h        |    1 +
 kernel/rcutree_plugin.h |    1 +
 kernel/rcutree_trace.c  |    1 +
 3 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 4a39d36..a5e9643 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -290,6 +290,7 @@ struct rcu_data {
 	unsigned long	n_force_qs_snap;
 					/* did other CPU force QS recently? */
 	long		blimit;		/* Upper limit on a processed batch */
+	unsigned long	n_defer_special;/* # of deferred _special() */
 
 	/* 3) dynticks interface. */
 	struct rcu_dynticks *dynticks;	/* Shared per-CPU dynticks state. */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index c9ff9f1..d828eec 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -396,6 +396,7 @@ void rcu_read_unlock_special(struct task_struct *t, bool unlock)
 		 * is still unlikey to be true.
 		 */
 		if (unlikely(unlock && irqs_disabled_flags(flags))) {
+			this_cpu_ptr(&rcu_preempt_data)->n_defer_special++;
 			set_need_resched();
 			local_irq_restore(flags);
 			return;
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index cf6c174..17d8b2c 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -149,6 +149,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
 	seq_printf(m, " ci=%lu nci=%lu co=%lu ca=%lu\n",
 		   rdp->n_cbs_invoked, rdp->n_nocbs_invoked,
 		   rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
+	seq_printf(m, " ds=%lu\n", rdp->n_defer_special);
 }
 
 static int show_rcudata(struct seq_file *m, void *v)
-- 
1.7.4.4

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