perf_counter: add some comments

Add a few comments because I was forgetting what field what for what functionality. Signed-off-by: Peter Zijlstra <[email protected]> Cc: Paul Mackerras <[email protected]> Cc: Corey Ashford <[email protected]> LKML-Reference: <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
mna · Apr 8, 2009 · 8740f94 · 8740f94
1 parent 808382b
commit 8740f94
Showing 1 changed file with 6 additions and 4 deletions.
diff --git 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];
 };