This will be useful to be put inside loops.
Suggested-by: Andrew Jones <drjones@xxxxxxxxxx>
Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
---
lib/x86/asm/barrier.h | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/lib/x86/asm/barrier.h b/lib/x86/asm/barrier.h
index 7c108bd..193fb4c 100644
--- a/lib/x86/asm/barrier.h
+++ b/lib/x86/asm/barrier.h
@@ -13,4 +13,15 @@
#define smp_rmb() barrier()
#define smp_wmb() barrier()
+/* REP NOP (PAUSE) is a good thing to insert into busy-wait loops. */
+static inline void rep_nop(void)
+{
+ asm volatile("rep; nop" ::: "memory");
+}
+
+static inline void cpu_relax(void)
+{
+ rep_nop();
+}
+
#endif
--
2.7.4
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