[dpdk-dev] [PATCH v3 2/2] ring: use wfe to wait for ring tail update on aarch64

[Ruifeng Wang]

Instead of polling for tail to be updated, use wfe instruction.

Signed-off-by: Gavin Hu <gavin.hu at arm.com>
Signed-off-by: Ruifeng Wang <ruifeng.wang at arm.com>
Reviewed-by: Steve Capper <steve.capper at arm.com>
Reviewed-by: Ola Liljedahl <ola.liljedahl at arm.com>
Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
---
 lib/ring/rte_ring_c11_pvt.h     | 4 ++--
 lib/ring/rte_ring_generic_pvt.h | 3 +--
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/lib/ring/rte_ring_c11_pvt.h b/lib/ring/rte_ring_c11_pvt.h
index 759192f4c4..37e0b2afd6 100644
--- a/lib/ring/rte_ring_c11_pvt.h
+++ b/lib/ring/rte_ring_c11_pvt.h
@@ -2,6 +2,7 @@
  *
  * Copyright (c) 2017,2018 HXT-semitech Corporation.
  * Copyright (c) 2007-2009 Kip Macy kmacy at freebsd.org
+ * Copyright (c) 2021 Arm Limited
  * All rights reserved.
  * Derived from FreeBSD's bufring.h
  * Used as BSD-3 Licensed with permission from Kip Macy.
@@ -21,8 +22,7 @@ __rte_ring_update_tail(struct rte_ring_headtail *ht, uint32_t old_val,
 	 * we need to wait for them to complete
 	 */
 	if (!single)
-		while (unlikely(ht->tail != old_val))
-			rte_pause();
+		rte_wait_until_equal_32(&ht->tail, old_val, __ATOMIC_RELAXED);
 
 	__atomic_store_n(&ht->tail, new_val, __ATOMIC_RELEASE);
 }
diff --git a/lib/ring/rte_ring_generic_pvt.h b/lib/ring/rte_ring_generic_pvt.h
index 532deb5e7a..c95ad7e12c 100644
--- a/lib/ring/rte_ring_generic_pvt.h
+++ b/lib/ring/rte_ring_generic_pvt.h
@@ -23,8 +23,7 @@ __rte_ring_update_tail(struct rte_ring_headtail *ht, uint32_t old_val,
 	 * we need to wait for them to complete
 	 */
 	if (!single)
-		while (unlikely(ht->tail != old_val))
-			rte_pause();
+		rte_wait_until_equal_32(&ht->tail, old_val, __ATOMIC_RELAXED);
 
 	ht->tail = new_val;
 }
-- 
2.25.1