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From: Phil Yang <phil.yang@arm.com>
To: david.marchand@redhat.com, dev@dpdk.org
Cc: drc@linux.vnet.ibm.com, Honnappa.Nagarahalli@arm.com,
	olivier.matz@6wind.com, ruifeng.wang@arm.com, nd@arm.com
Subject: [dpdk-dev] [PATCH v2] mbuf: use C11 atomics for refcnt operations
Date: Tue,  7 Jul 2020 18:10:33 +0800
Message-ID: <1594116633-14554-1-git-send-email-phil.yang@arm.com> (raw)
In-Reply-To: <1591871178-12542-1-git-send-email-phil.yang@arm.com>

Use C11 atomics with explicit ordering instead of rte_atomic ops which
enforce unnecessary barriers on aarch64.

Signed-off-by: Phil Yang <phil.yang@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
---
v2:
Fix ABI issue: revert the rte_mbuf_ext_shared_info struct refcnt field
to refcnt_atomic.

 lib/librte_mbuf/rte_mbuf.c      |  1 -
 lib/librte_mbuf/rte_mbuf.h      | 19 ++++++++++---------
 lib/librte_mbuf/rte_mbuf_core.h | 11 +++--------
 3 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/lib/librte_mbuf/rte_mbuf.c b/lib/librte_mbuf/rte_mbuf.c
index ae91ae2..8a456e5 100644
--- a/lib/librte_mbuf/rte_mbuf.c
+++ b/lib/librte_mbuf/rte_mbuf.c
@@ -22,7 +22,6 @@
 #include <rte_eal.h>
 #include <rte_per_lcore.h>
 #include <rte_lcore.h>
-#include <rte_atomic.h>
 #include <rte_branch_prediction.h>
 #include <rte_mempool.h>
 #include <rte_mbuf.h>
diff --git a/lib/librte_mbuf/rte_mbuf.h b/lib/librte_mbuf/rte_mbuf.h
index f8e492e..4a7a98c 100644
--- a/lib/librte_mbuf/rte_mbuf.h
+++ b/lib/librte_mbuf/rte_mbuf.h
@@ -37,7 +37,6 @@
 #include <rte_config.h>
 #include <rte_mempool.h>
 #include <rte_memory.h>
-#include <rte_atomic.h>
 #include <rte_prefetch.h>
 #include <rte_branch_prediction.h>
 #include <rte_byteorder.h>
@@ -365,7 +364,7 @@ rte_pktmbuf_priv_flags(struct rte_mempool *mp)
 static inline uint16_t
 rte_mbuf_refcnt_read(const struct rte_mbuf *m)
 {
-	return (uint16_t)(rte_atomic16_read(&m->refcnt_atomic));
+	return __atomic_load_n(&m->refcnt, __ATOMIC_RELAXED);
 }
 
 /**
@@ -378,14 +377,15 @@ rte_mbuf_refcnt_read(const struct rte_mbuf *m)
 static inline void
 rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
 {
-	rte_atomic16_set(&m->refcnt_atomic, (int16_t)new_value);
+	__atomic_store_n(&m->refcnt, new_value, __ATOMIC_RELAXED);
 }
 
 /* internal */
 static inline uint16_t
 __rte_mbuf_refcnt_update(struct rte_mbuf *m, int16_t value)
 {
-	return (uint16_t)(rte_atomic16_add_return(&m->refcnt_atomic, value));
+	return (uint16_t)(__atomic_add_fetch((int16_t *)&m->refcnt, value,
+					__ATOMIC_ACQ_REL));
 }
 
 /**
@@ -466,7 +466,7 @@ rte_mbuf_refcnt_set(struct rte_mbuf *m, uint16_t new_value)
 static inline uint16_t
 rte_mbuf_ext_refcnt_read(const struct rte_mbuf_ext_shared_info *shinfo)
 {
-	return (uint16_t)(rte_atomic16_read(&shinfo->refcnt_atomic));
+	return __atomic_load_n(&shinfo->refcnt_atomic, __ATOMIC_RELAXED);
 }
 
 /**
@@ -481,7 +481,7 @@ static inline void
 rte_mbuf_ext_refcnt_set(struct rte_mbuf_ext_shared_info *shinfo,
 	uint16_t new_value)
 {
-	rte_atomic16_set(&shinfo->refcnt_atomic, (int16_t)new_value);
+	__atomic_store_n(&shinfo->refcnt_atomic, new_value, __ATOMIC_RELAXED);
 }
 
 /**
@@ -505,7 +505,8 @@ rte_mbuf_ext_refcnt_update(struct rte_mbuf_ext_shared_info *shinfo,
 		return (uint16_t)value;
 	}
 
-	return (uint16_t)rte_atomic16_add_return(&shinfo->refcnt_atomic, value);
+	return (uint16_t)(__atomic_add_fetch((int16_t *)&shinfo->refcnt_atomic,
+					    value, __ATOMIC_ACQ_REL));
 }
 
 /** Mbuf prefetch */
@@ -1304,8 +1305,8 @@ static inline int __rte_pktmbuf_pinned_extbuf_decref(struct rte_mbuf *m)
 	 * Direct usage of add primitive to avoid
 	 * duplication of comparing with one.
 	 */
-	if (likely(rte_atomic16_add_return
-			(&shinfo->refcnt_atomic, -1)))
+	if (likely(__atomic_add_fetch((int *)&shinfo->refcnt_atomic, -1,
+				     __ATOMIC_ACQ_REL)))
 		return 1;
 
 	/* Reinitialize counter before mbuf freeing. */
diff --git a/lib/librte_mbuf/rte_mbuf_core.h b/lib/librte_mbuf/rte_mbuf_core.h
index 16600f1..806313a 100644
--- a/lib/librte_mbuf/rte_mbuf_core.h
+++ b/lib/librte_mbuf/rte_mbuf_core.h
@@ -18,7 +18,6 @@
 
 #include <stdint.h>
 #include <rte_compat.h>
-#include <generic/rte_atomic.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -495,12 +494,8 @@ struct rte_mbuf {
 	 * or non-atomic) is controlled by the CONFIG_RTE_MBUF_REFCNT_ATOMIC
 	 * config option.
 	 */
-	RTE_STD_C11
-	union {
-		rte_atomic16_t refcnt_atomic; /**< Atomically accessed refcnt */
-		/** Non-atomically accessed refcnt */
-		uint16_t refcnt;
-	};
+	uint16_t refcnt;
+
 	uint16_t nb_segs;         /**< Number of segments. */
 
 	/** Input port (16 bits to support more than 256 virtual ports).
@@ -679,7 +674,7 @@ typedef void (*rte_mbuf_extbuf_free_callback_t)(void *addr, void *opaque);
 struct rte_mbuf_ext_shared_info {
 	rte_mbuf_extbuf_free_callback_t free_cb; /**< Free callback function */
 	void *fcb_opaque;                        /**< Free callback argument */
-	rte_atomic16_t refcnt_atomic;        /**< Atomically accessed refcnt */
+	uint16_t refcnt_atomic;              /**< Atomically accessed refcnt */
 };
 
 /**< Maximum number of nb_segs allowed. */
-- 
2.7.4


  parent reply	other threads:[~2020-07-07 10:10 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-11 10:26 [dpdk-dev] [PATCH] mbuf: use c11 " Phil Yang
2020-07-03 15:38 ` David Marchand
2020-07-06  8:03   ` Phil Yang
2020-07-07 10:10 ` Phil Yang [this message]
2020-07-07 17:13   ` [dpdk-dev] [PATCH v2] mbuf: use C11 " Stephen Hemminger
2020-07-08  4:48     ` Phil Yang
2020-07-08 11:43       ` Olivier Matz
2020-07-09  9:52         ` Phil Yang
2020-07-08  5:11   ` Phil Yang
2020-07-08 11:44   ` Olivier Matz
2020-07-09 10:00     ` Phil Yang
2020-07-09 10:10   ` [dpdk-dev] [PATCH v3] mbuf: use C11 atomic built-ins " Phil Yang
2020-07-09 11:03     ` Olivier Matz
2020-07-09 13:00       ` Phil Yang
2020-07-09 13:31         ` Honnappa Nagarahalli
2020-07-09 14:10           ` Phil Yang
2020-07-09 15:58     ` [dpdk-dev] [PATCH v4 1/2] " Phil Yang
2020-07-09 15:58       ` [dpdk-dev] [PATCH v4 2/2] doc: announce deprecation of refcnt atomic member Phil Yang
2020-07-10  2:55         ` Ruifeng Wang
2020-07-13 15:54           ` Phil Yang
2020-07-14 10:41         ` Ananyev, Konstantin
2020-07-15 12:29       ` [dpdk-dev] [PATCH v4 1/2] mbuf: use C11 atomic built-ins for refcnt operations David Marchand
2020-07-15 12:49         ` Aaron Conole
2020-07-15 16:29         ` Phil Yang
2020-07-16  4:16         ` Phil Yang
2020-07-16 11:30           ` David Marchand
2020-07-16 13:20             ` Dodji Seketeli
2020-07-16 19:11               ` David Marchand
2020-07-17  4:41                 ` Phil Yang
2020-07-16 11:32       ` Olivier Matz
2020-07-17  4:36       ` [dpdk-dev] [PATCH v5 1/2] mbuf: use C11 atomic builtins " Phil Yang
2020-07-17  4:36         ` [dpdk-dev] [PATCH v5 2/2] doc: announce deprecation of refcnt atomic member Phil Yang
2020-07-17 11:45           ` Olivier Matz
2020-07-17 14:32           ` David Marchand
2020-07-17 14:35             ` David Marchand
2020-07-17 16:06               ` Ananyev, Konstantin
2020-07-17 16:20               ` Bruce Richardson
2020-07-21  8:35                 ` David Marchand
2020-07-21  8:48                   ` Ananyev, Konstantin
2020-07-21  8:37         ` [dpdk-dev] [PATCH v5 1/2] mbuf: use C11 atomic builtins for refcnt operations David Marchand

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