[PATCH 5/9] perf_counter: add some comments

[Peter Zijlstra <a.p.zijlstra@chello.nl>]

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Add a few comments because I was forgetting what field what for what
functionality.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/perf_counter.h |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: linux-2.6/include/linux/perf_counter.h
===================================================================
--- linux-2.6.orig/include/linux/perf_counter.h
+++ linux-2.6/include/linux/perf_counter.h
@@ -347,10 +347,12 @@ 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];
 };

--