perf: Optimize the hotpath by converting the perf output buffer to local_t

Since there is now only a single writer, we can use
local_t instead and avoid all these pesky LOCK insn.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 7 insertions, 8 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index f1f853a9d5eb..ce7667616fcb 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -485,6 +485,7 @@ struct perf_guest_info_callbacks {
 #include <linux/ftrace.h>
 #include <linux/cpu.h>
 #include <asm/atomic.h>
+#include <asm/local.h>
 
 #define PERF_MAX_STACK_DEPTH            255
 
@@ -588,20 +589,18 @@ struct perf_mmap_data {
 #ifdef CONFIG_PERF_USE_VMALLOC
         struct work_struct              work;
 #endif
-        int                             data_order;
+        int                             data_order;     /* allocation order  */
         int                             nr_pages;       /* nr of data pages  */
         int                             writable;       /* are we writable   */
         int                             nr_locked;      /* nr pages mlocked  */
 
         atomic_t                        poll;           /* POLL_ for wakeups */
-        atomic_t                        events;         /* event_id limit       */
 
-        atomic_long_t                   head;           /* write position    */
-
-        atomic_t                        wakeup;         /* needs a wakeup    */
-        atomic_t                        lost;           /* nr records lost   */
-
-        atomic_t                        nest;           /* nested writers    */
+        local_t                         head;           /* write position    */
+        local_t                         nest;           /* nested writers    */
+        local_t                         events;         /* event limit       */
+        local_t                         wakeup;         /* needs a wakeup    */
+        local_t                         lost;           /* nr records lost   */
 
         long                            watermark;      /* wakeup watermark  */