In acquiring a spinlock, cores repeatedly poll the lock variable.
This is replaced by rte_wait_until_equal API.
5~10% performance gain was measured by running spinlock_autotest on
14 isolated cores of ThunderX2.
Signed-off-by: Gavin Hu <gavin...@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.w...@arm.com>
Reviewed-by: Phil Yang <phil.y...@arm.com>
Reviewed-by: Steve Capper <steve.cap...@arm.com>
Reviewed-by: Ola Liljedahl <ola.liljed...@arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com>
---
.../common/include/arch/arm/rte_spinlock.h | 25 ++++++++++++++++++++++
.../common/include/generic/rte_spinlock.h | 2 +-
2 files changed, 26 insertions(+), 1 deletion(-)
diff --git a/lib/librte_eal/common/include/arch/arm/rte_spinlock.h
b/lib/librte_eal/common/include/arch/arm/rte_spinlock.h
index 1a6916b..f25d17f 100644
--- a/lib/librte_eal/common/include/arch/arm/rte_spinlock.h
+++ b/lib/librte_eal/common/include/arch/arm/rte_spinlock.h
@@ -16,6 +16,31 @@ extern "C" {
#include <rte_common.h>
#include "generic/rte_spinlock.h"
+/* armv7a does support WFE, but an explicit wake-up signal using SEV is
+ * required (must be preceded by DSB to drain the store buffer) and
+ * this is less performant, so keep armv7a implementation unchanged.
+ */
+#if defined(RTE_USE_WFE) && defined(RTE_ARCH_ARM64)
+static inline void
+rte_spinlock_lock(rte_spinlock_t *sl)
+{
+ unsigned int tmp;
+ /* http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.
+ * faqs/ka16809.html
+ */
+ asm volatile(
+ "sevl\n"
+ "1: wfe\n"
+ "2: ldaxr %w[tmp], %w[locked]\n"
+ "cbnz %w[tmp], 1b\n"
+ "stxr %w[tmp], %w[one], %w[locked]\n"
+ "cbnz %w[tmp], 2b\n"
+ : [tmp] "=&r" (tmp), [locked] "+Q"(sl->locked)
+ : [one] "r" (1)
+ : "cc", "memory");
+}
+#endif
+
static inline int rte_tm_supported(void)
{
return 0;
diff --git a/lib/librte_eal/common/include/generic/rte_spinlock.h
b/lib/librte_eal/common/include/generic/rte_spinlock.h
index 87ae7a4..cf4f15b 100644
--- a/lib/librte_eal/common/include/generic/rte_spinlock.h
+++ b/lib/librte_eal/common/include/generic/rte_spinlock.h
@@ -57,7 +57,7 @@ rte_spinlock_init(rte_spinlock_t *sl)
static inline void
rte_spinlock_lock(rte_spinlock_t *sl);
-#ifdef RTE_FORCE_INTRINSICS
+#if defined(RTE_FORCE_INTRINSICS) && !defined(RTE_USE_WFE)
static inline void
rte_spinlock_lock(rte_spinlock_t *sl)
{
--
2.7.4
