[dpdk-dev] [PATCH] EAL:fix memory barrier implementation on IBM POWER

[dpdk-dev] [PATCH] EAL:fix memory barrier implementation on IBM POWER

[Chao Zhu]

On weak memory order architecture like POWER, rte_smp_wmb/rte_smp_rmb
need to use CPU instructions, not compiler barrier. This patch fixes
this. Also, to improve performance on PPC64, use light weight sync
instruction instead of sync instruction.

Signed-off-by: Chao Zhu <chaozhu@linux.vnet.ibm.com>
---
 .../common/include/arch/ppc_64/rte_atomic.h        |   12 ++++++++++--
 1 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h b/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
index feae486..924e894 100644
--- a/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
+++ b/lib/librte_eal/common/include/arch/ppc_64/rte_atomic.h
@@ -62,7 +62,11 @@ extern "C" {
  * Guarantees that the STORE operations generated before the barrier
  * occur before the STORE operations generated after.
  */
+#ifdef RTE_ARCH_64
+#define	rte_wmb() {asm volatile("lwsync" : : : "memory"); }
+#else
 #define	rte_wmb() {asm volatile("sync" : : : "memory"); }
+#endif
 
 /**
  * Read memory barrier.
@@ -70,13 +74,17 @@ extern "C" {
  * Guarantees that the LOAD operations generated before the barrier
  * occur before the LOAD operations generated after.
  */
+#ifdef RTE_ARCH_64
+#define	rte_rmb() {asm volatile("lwsync" : : : "memory"); }
+#else
 #define	rte_rmb() {asm volatile("sync" : : : "memory"); }
+#endif
 
 #define rte_smp_mb() rte_mb()
 
-#define rte_smp_wmb() rte_compiler_barrier()
+#define rte_smp_wmb() rte_wmb()
 
-#define rte_smp_rmb() rte_compiler_barrier()
+#define rte_smp_rmb() rte_rmb()
 
 /*------------------------- 16 bit atomic operations -------------------------*/
 /* To be compatible with Power7, use GCC built-in functions for 16 bit
-- 
1.7.1

Re: [dpdk-dev] [PATCH] EAL:fix memory barrier implementation on IBM POWER

[Thomas Monjalon]

2016-07-15 10:30, Chao Zhu:
> On weak memory order architecture like POWER, rte_smp_wmb/rte_smp_rmb
> need to use CPU instructions, not compiler barrier. This patch fixes
> this. Also, to improve performance on PPC64, use light weight sync
> instruction instead of sync instruction.
> 
> Signed-off-by: Chao Zhu <chaozhu@linux.vnet.ibm.com>

Applied, thanks