1 files changed, 6 insertions, 4 deletions
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 4809ae18a94..8bf764fc622 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -344,10 +344,12 @@ struct file;
 
 struct perf_mmap_data {
 	struct rcu_head			rcu_head;
-	int				nr_pages;
-	atomic_t			wakeup;
-	atomic_t			head;
-	atomic_t			events;
+	int				nr_pages;	/* nr of data pages  */
+
+	atomic_t			wakeup;		/* POLL_ for wakeups */
+	atomic_t			head;		/* write position    */
+	atomic_t			events;		/* event limit       */
+
 	struct perf_counter_mmap_page   *user_page;
 	void 				*data_pages[0];
 };