perf: Optimize perf_output_*() by avoiding local_xchg()
Since the x86 XCHG ins implies LOCK, avoid the use by
using a sequence count instead.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index ce76676..fe50347 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -804,6 +804,7 @@
struct perf_mmap_data *data;
unsigned long head;
unsigned long offset;
+ unsigned long wakeup;
int nmi;
int sample;
};