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Subject[tip:perfcounters/core] perf_counter: add some comments
Commit-ID:  8740f9418c78dcad694b46ab25d1645d5aef1f5e
Gitweb: http://git.kernel.org/tip/8740f9418c78dcad694b46ab25d1645d5aef1f5e
Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
AuthorDate: Wed, 8 Apr 2009 15:01:29 +0200
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 8 Apr 2009 18:53:29 +0200

perf_counter: add some comments

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

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
LKML-Reference: <20090408130409.036984214@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>


---
include/linux/perf_counter.h | 10 ++++++----
1 files changed, 6 insertions(+), 4 deletions(-)
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 4809ae1..8bf764f 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];
};

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